Lidar system and method

ABSTRACT

A Lidar system may comprise a rotor and a stator. The rotor is configured to rotate with respect to the stator. The rotor comprises at least one supporting body and a plurality of light sources disposed on the at least one supporting body, the plurality of light sources configured to emit a plurality of first light beams. The plurality of light beams are non-uniformly distributed along a vertical direction in a vertical field of view of the Lidar system.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/564,842, filed Sep. 9, 2019, which is a continuation of U.S.patent application Ser. No. 16/011,127, filed Jun. 18, 2018, now U.S.Pat. No. 10,473,767, which is based on and claims priority to theChinese Patent Application No. 201810036235.4, filed Jan. 15, 2018, theChinese Patent Application No. 201710463616.6, filed Jun. 19, 2017, theChinese Patent Application No. 201810045754.7, filed Jan. 17, 2018, theChinese Patent Application No. 201810045703.4, filed Jan. 17, 2018, andthe International Patent Application No. PCT/CN2018/081367, filed Mar.30, 2018. The entire contents of all of the above applications areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the field of semiconductortechnologies, and in particular, to Lidar (light detection and ranging)systems and methods.

BACKGROUND

At present, in order to obtain sufficient three-dimensional information,a multiline Lidar having a large vertical field of view is usually used.A large area scan can be achieved by rotating Lidar and thereby rotatingthe vertical field of view with the Lidar. The angular distribution ofbeams in an existing multiline Lidar device is uniform within aparticular angle range (that is, the angular distribution of laser beamsin the vertical field of view is constant, and the vertical angularresolution is thus constant). For example, the vertical angularresolutions of 16-line, 32-line, and 64-line Lidars are respectively 2°,1.33°, and 0.43°. For another example, the vertical angular resolutionsof 4-line and 8-line Lidars are each 0.8°.

The constant vertical angular resolution can cause significantperformance issues for the Lidar. For example, in some applications, aLidar may be mounted on a vehicle to detect pedestrians, other vehicles,and the like on the ground. Assuming that the laser beams diverge fromthe Lidar in vertical planes, laser beams emitted upwards are mostlywasted because the main detection targets for Lidar are more likely tobe on the same elevation level as the Lidar-mounted vehicle, and aresubstantially covered by horizontally emitted laser beams, making somenon-horizontal beams like the upward beams excessive. By the samereason, insufficient horizontal beams incident on the main detectiontargets can result in low accuracies for their detections.

In addition, if the angular distribution of laser beams remains constantin the vertical field of view according to existing Lidar technologies,more laser lines are needed to achieve a higher vertical resolution,which results in a higher cost, a larger Lidar size, and a lowerreliability and stability. Limited by the data capacity of Ethernet andthe processing speed of in-vehicle CPU, a Lidar with more lines cannotachieve both high horizontal angular resolution and high scanningfrequency.

However, if the number of lines are reduced to lower the cost whilekeeping the angular distribution of laser beams constant, the angularinterval between laser beams becomes excessively large, and a target maynot be recognized within a reasonable detection range (e.g., 40 metersaway). For example, if the total vertical field of view is 32 and theinterval (the vertical resolution) is 2°, 16 lines are needed, and thenthe intervals among laser beams 40 meters away are approximately 1.4 m.Due to the large interval of 1.4 m, a pedestrian at that position may beundetected.

SUMMARY

To at least mitigate the problems (e.g., unutilized upward beams, lowaccuracy for detecting main targets, high cost, packaging difficulty)set forth above in current technologies, various Lidar systems andmethods are disclosed.

According to one aspect, a Lidar system comprises a rotor and a stator.The rotor is configured to rotate with respect to the stator. The rotorcomprises at least one supporting body and a plurality of light sourcesdisposed on the at least one supporting body, the plurality of lightsources configured to emit a plurality of first light beams. Theplurality of first light beams are non-uniformly distributed along avertical direction in a vertical field of view of the Lidar system.

In some embodiments, the at least one supporting body comprise aplurality of the supporting bodies disposed non-uniformly along thevertical direction in the vertical field of view of the Lidar, causingthe plurality of first light beams to non-uniformly distribute along thevertical direction in the vertical field of view of the Lidar.

In some embodiments, the plurality of light sources comprise one or morelasers disposed on each of the supporting bodies; and a concentration ofthe lasers first increases and then decreases along a vertical directionfrom a highest laser to a lowest laser of the lasers.

In some embodiments, the non-uniform distribution of the plurality offirst light beams along the vertical direction comprises a sparserconcentration of the first light beams at each of two ends of thevertical field of view of the Lidar and a denser concentration of thefirst light beams towards center of the vertical field of view of theLidar.

In some embodiments, the Lidar system further comprises: an opticalsplitting apparatus configured to split each of the first light beamsinto a plurality of third light beams with different propagationdirections, wherein the third light beams are non-uniformly distributedalong the vertical direction in the vertical field of view of the Lidarsystem.

In some embodiments, the optical splitting apparatus comprises at leastone of a grating, an optical fiber beam splitter, a plane diffractiongrating, a blazed grating, or a lens combination.

In some embodiments, the grating comprises a Dammann grating.

In some embodiments, the optical splitting apparatus comprises an m by 1one-dimensional grating configured to rotate about an axis normal to thegrating for less than:

${\arccos\left( \frac{d\mspace{14mu} \sin \frac{\alpha}{m}}{\lambda} \right)},$

the grating has a grating period d₁ the first light beams have awavelength λ, a number of the third light beams is m; and a preset fieldof view of the third light beams is α. In some embodiments, the gratingperiod d is between 47 μm and 57 μm; and the wavelength λ is between 895nm and 915 nm.

In some embodiments, the optical splitting apparatus comprises a m by ntwo-dimensional grating configured to rotate about an axis normal to aplane of the grating for an angle between:

${0.9\mspace{14mu} {\arctan \left( \frac{\arcsin \left( \frac{\lambda}{d_{1}} \right)}{m \times {\arcsin \left\lbrack \frac{\lambda}{d_{2}} \right\rbrack}} \right)}\mspace{14mu} {and}\mspace{14mu} 1.1{\arctan \left( \frac{\arcsin \left( \frac{\lambda}{d_{1}} \right)}{m \times {\arcsin \left\lbrack \frac{\lambda}{d_{2}} \right\rbrack}} \right)}},$

the two-dimensional grating has a period d₁ along one dimension andanother period d₂ along the other dimension; the first light beams havea wavelength λ; m is a number of the third light beams in the d₁direction; and n is a number of the third light beams in the d₂direction. In some embodiments, the period d₁ is between 47 μm and 57μm; the period d₂ is between 47 μm and 57 μm; and the wavelength λ isbetween 895 nm and 915 nm.

In some embodiments, the Lidar system further comprises a galvanometer,wherein: the galvanometer is configured to rotate about a vibrationrotating shaft; the galvanometer comprises a first reflecting surfaceconfigured to reflect the third light beams out of the Lidar during therotation of the galvanometer; and an angle between the vibrationrotating shaft and a normal line of the first reflecting surface islarger than zero.

In some embodiments, the optical splitting apparatus comprises aone-dimensional grating; the third light beams reaching the firstreflecting surface are in a propagation plane; the first reflectingsurface and the propagation plane have an intersecting line; and anangle between the vibration rotating shaft and the intersecting line islarger than 0 degrees.

In some embodiments, the Lidar system further comprises a scanningrotating shaft intersected with a propagation direction of the firstlight beams, wherein an angle between the vibration rotating shaft andthe scanning rotating shaft is larger than 0 degrees.

In some embodiments, the Lidar system further comprises: a collimatinglens configured to collimate the third light beams to progagate inparallel directions; and a focusing lens configured to converge thecollimated third light beams to the first reflecting surface of thegalvanometer.

In some embodiments, the Lidar system further comprises: asemi-transparent mirror and a receiving device, wherein: at least aportion of the third light beams passes through the optical splittingapparatus and the semi-transparent mirror to reach a first reflectingsurface of the galvanometer; at least a portion of the third light beamsreflected by the first reflecting surface is reflected back to the firstreflecting surface as echo beams; and the semi-transparent mirrorcomprises a second reflecting surface configured to reflect the echolight beams reflected by the first reflecting surface into the receivingdevice.

In some embodiments, the Lidar system further comprises a receivingconverging lens, wherein: the receiving converging lens is configured toconverge the echo light beams reflected by the semi-transparent mirrorinto the receiving device; and a distance between the receiving deviceand a focal point of the receiving converging lens is smaller than halfof a focal depth of the receiving converging lens.

In some embodiments, the first light beams propagate in differentdirections. Each two of the first light beams intersect.

In some embodiments, the Lidar system further comprises a converginglens configured to converge the first light beams to the opticalsplitting apparatus, wherein: the first light beams are parallel to eachother; and a distance from the optical splitting apparatus to a focalplane of the converging lens is less than half of a focal depth of theconverging lens.

According to another aspect, a Lidar may comprise: a rotor and a stator,wherein the rotor comprises: one or more supporting bodies verticallydisposed in the rotor; and a plurality of lasers disposed on each of thesupporting bodies and configured to emit laser beams respectively,wherein the lasers are distributed non-uniformly along a verticaldirection from a highest to a lowest of the lasers.

According to another aspect, a Lidar system may comprise: an emittingapparatus comprising a plurality of lasers configured to emit laserbeams respectively in an emission direction; an optical splittingapparatus configured to receive and split the laser beams into aplurality of split laser beams with different propagation directions,and a receiving apparatus configured to receive echo beams to detect atarget, wherein the echo beams are a portion of the split beamsreflected by the target. The lasers are non-uniformly disposed in adistribution direction normal to the emission direction, a concentrationof the lasers first increases and then decreases along the distributiondirection, and at least some of the split laser beams overlap.

According to another aspect, a Lidar system may comprise an emittingapparatus and a receiving apparatus. The emitting apparatus may comprisea first laser, a second laser, and an optical splitting apparatus. Thefirst laser is configured to emit a first laser beam, and the secondlaser is configured to emit a second laser beam. The optical splittingapparatus is configured to split the first laser beam into a pluralityof third laser beams with different propagation directions, and splitthe second laser beam into a plurality of fourth laser beams withdifferent propagation directions. The third laser beams at leastpartially overlap with the fourth laser beams at an overlapping region.The receiving apparatus is configured to receive echo beams reflectedfrom at least one of the third laser beams or the fourth laser beams bya target.

In some embodiments, the target reflects a portion of the third laserbeams and a portion of the fourth laser beams simultaneously in theoverlapping region to form the echo beams.

In some embodiments, the Lidar is mounted on a vehicle configured tomove on a surface and is rotatable with respect to a vertical axisrelative to the surface. The first and second lasers are disposed in avertical plane relative to the surface and configured to emit the firstand second laser beams respectively in a direction along the surface.When the Lidar is not rotating with respect to the vertical axis, thefirst, second, third, and fourth laser beams propagate in the verticalplane, causing the third and fourth laser beams to scan a distantvertical line. When the Lidar is rotating with respect to the verticalaxis, the vertical plane rotates with respect to the vertical axis,causing the third and fourth laser beams to scan a distant verticalsurface.

In some embodiments, the emitting apparatus further comprises a rotatingshaft. The Lidar is configured to rotate about the rotating shaft, therotating shaft acting as the vertical axis. The third and fourth laserbeams diverge from the Lidar. The first, second, third, and fourth laserbeams and the rotating shaft are in the vertical plane.

In some embodiments, the optical splitting apparatus comprises aone-dimensional or two-dimensional Dammann grating.

In some embodiments, the optical splitting apparatus comprises anoptical fiber beam splitter.

In some embodiments, the Lidar system further comprises: a first beamexpanding and collimating apparatus configured to increase a spotdiameter of the first laser beam and reduce a divergence angle of thefirst laser beam; and a second beam expanding and collimating apparatusconfigured to increase a spot diameter of the second laser beam andreduce a divergence angle of the second laser beam.

In some embodiments, the emitting apparatus further comprises a firstconverging lens configured to converge the first and second laser beamsto the optical splitting apparatus. A distance from the opticalsplitting apparatus to a focal plane of the first converging lens isless than half of a focal depth of the first converging lens.

In some embodiments, the emitting apparatus further comprises a rotatingshaft. The Lidar is configured to rotate about the rotating shaft. Anoptical axis of the first converging lens is perpendicular to therotating shaft. The lasers are arranged in a vertical plane along adirection parallel to the rotating shaft. The first and second laserbeams propagate in parallel to the optical axis of the first converginglens.

In some embodiments, the receiving apparatus comprises: a first detectorconfigured to receive echo beams that are reflected off the target fromthe third laser beams for detecting the target; and a second detectorconfigured to receive echo beams that are reflected off the target fromthe fourth laser beams for detecting the target.

According to another aspect, a Lidar system may comprise: an emittingapparatus configured to emit a first laser beam to a to-be-detectedtarget; an optical splitting apparatus configured to split the firstlaser beam into a plurality of third laser beams propagating alongdifferent directions, where the third laser beams are reflected by theto-be-detected target to form echo beams; and a receiving apparatus,configured to receive the echo beams.

In some embodiments, the emitting apparatus is configured to rotatearound a rotating shaft, an angle between the first laser beam and therotating shaft is greater than zero, and the plurality of third laserbeams propagate in different angles with respect to the rotating shaft.

In some embodiments, the optical splitting apparatus comprises a Dammanngrating or an optical fiber beam splitter, and the Dammann grating is aone-dimensional Dammann grating or a two-dimensional Dammann grating.

In some embodiments, the Lidar further includes a beam expanding andcollimating apparatus configured to: increase a spot diameter of thefirst laser beam, and reduce a divergence angle of the first laser beam.

In some embodiments, the emitting apparatus is configured tosimultaneously emit the plurality of third laser beams with differentpropagation directions.

In some embodiments, the emitting apparatus includes a plurality oflasers, and propagation directions of laser beams emitted by theplurality of lasers are different.

In some embodiments, the emitting apparatus includes a plurality oflasers and a first converging lens, propagation directions of laserbeams emitted by the plurality of lasers are the same, the firstconverging lens is configured to converge the laser beams emitted by theplurality of lasers to the optical splitting apparatus, and a distancefrom the optical splitting apparatus to a focal plane of the firstconverging lens is less than half of a focal depth of the firstconverging lens.

In some embodiments, the emitting apparatus has a rotating shaft, theemitting apparatus is configured to rotate about the rotating shaft, anangle between the first laser beam and the rotating shaft is greaterthan zero, an optical axis of the first converging lens is perpendicularto the rotating shaft, the plurality of lasers are arranged along adirection parallel to the rotating shaft, and the propagation directionsof the laser beams emitted by the plurality of lasers are parallel tothe optical axis of the first converging lens.

In some embodiments, the receiving apparatus includes a plurality ofdetectors, and the detectors are respectively configured to receive theecho beams formed by reflecting, by the to-be-detected target, thecorresponding laser beams emitted by the plurality of lasers.

According to another aspect, a detection method may comprise: emitting(e.g., from an emitting apparatus) a first laser beam towards a target,the first laser beam split by an optical splitting apparatus (e.g., anoptical splitting apparatus) into a plurality of third laser beams withdifferent propagation directions, wherein the third laser beams arereflected by the target as echo beams; receiving (e.g., by a receivingapparatus) the echo beams; and detecting the target based on the echobeams.

According to another aspect, a Lidar system may comprise a rotor and astator, wherein the rotor comprises: one or more supporting bodiesvertically disposed in the rotor; and a plurality of lasers disposed oneach of the supporting bodies and configured to emit laser beamsrespectively, wherein a concentration of the lasers first increases andthen decreases inside the rotor along a vertical direction from ahighest laser to a lowest laser of the lasers.

According to another aspect, a Lidar based on a plurality ofnon-uniformly distributed lasers may comprise a rotor and a stator. TheLidar may further include: a supporting body, provided with a pluralityof lasers and disposed in the rotor; and an optical collimation device,where projection points, on a vertical plane including a principal axisof the optical collimation device, of the lasers are distributed with avariable density in a vertical direction, and the optical collimationdevice is disposed in the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of lasers of a conventionalmultiline Lidar.

FIG. 2 is a view diagram of a Lidar, consistent with various embodimentsof the present disclosure.

FIG. 3 is a simplified structural diagram of a Lidar, consistent withvarious embodiments of the present disclosure.

FIG. 4A is a simplified structural diagram of a structure comprising asupporting body and lasers of a Lidar, consistent with variousembodiments of the present disclosure.

FIG. 4B is a simplified structural diagram of a structure comprising asupporting body and lasers of a Lidar, consistent with variousembodiments of the present disclosure.

FIG. 5 is a simplified structural diagram of a structure comprising aplurality of supporting bodies and lasers in an emitting cavity of aLidar, consistent with various embodiments of the present disclosure.

FIG. 6 is a simplified structural diagram of a structure comprising aplurality of supporting bodies and lasers in an emitting cavity of aLidar, consistent with various embodiments of the present disclosure.

FIG. 7 is a simplified structural diagram of a scanning apparatus in theLidar, consistent with various embodiments of the present disclosure.

FIG. 8 is a simplified structural diagram of a structure comprising aplurality of supporting bodies and lasers in a Lidar, consistent withvarious embodiments of the present disclosure.

FIG. 9 is a schematic structural diagram of an emitting apparatus of aLidar, consistent with various embodiments of the present disclosure.

FIG. 10 is a schematic structural diagram of a receiving apparatus of aLidar, consistent with various embodiments of the present disclosure.

FIG. 11A is a schematic structural diagram of an optical splittingapparatus of a Lidar, consistent with various embodiments of the presentdisclosure.

FIGS. 11B-11C are graphical diagrams of light spots formed on a targetplane by laser beams of a Lidar, consistent with various embodiments ofthe present disclosure.

FIG. 11D is a graphical diagram of light spots formed on a target planeby laser beams of a Lidar, consistent with various embodiments of thepresent disclosure.

FIGS. 11E-11G are light path diagrams of a Lidar, consistent withvarious embodiments of the present disclosure.

FIGS. 11H-11J are graphical diagrams of light spots formed by the laserbeams on a target plane at different times of galvanometer vibration,consistent with various embodiments of the present disclosure.

FIG. 12 is a schematic structural diagram of an emitting apparatus of aLidar, consistent with various embodiments of the present disclosure.

FIG. 13 is a schematic structural diagram of an emitting apparatus of aLidar, consistent with various embodiments of the present disclosure.

FIG. 14 is a graphical diagram illustrating light spots on a targetplane before and after the optical splitting apparatus rotation,consistent with various embodiments of the present disclosure.

FIG. 15 is a schematic structural diagram of an emitting apparatus of aLidar, consistent with various embodiments of the present disclosure.

FIG. 16 is a block diagram of a detection method, consistent withvarious embodiments of the present disclosure.

DETAILED DESCRIPTION

Lidar is a type of ranging sensor characterized by long detectiondistance, high resolution, and low interference by the environment.Lidar has been widely applied in the fields of intelligent robots,unmanned aerial vehicles, and self-driving. The working principle ofLidar is estimating a distance based on a round trip time ofelectromagnetic waves between a source and a target.

The earliest Lidar is a uniline Lidar, that is, a Lidar with only onelaser emitting one beam and one detector detecting one reflected beam. Atarget range scanned by the uniline Lidar is limited, easily causingincomplete detection of detection targets. To overcome the disadvantageof the uniline Lidar, multiline Lidar has been increasingly used inresearch and commercial applications. In the multiline Lidar, aplurality of lasers and corresponding detectors are arranged in avertical direction to increase the detection range in the verticaldirection.

FIG. 1 is a schematic structural diagram of lasers of a conventionalmultiline Lidar. Referring to FIG. 1, the conventional multiline Lidarincludes: a plurality of lasers 10 configured to emit laser beamsrespectively and a lens 20 configured to cause the laser beamsrespectively emitted by the lasers 10 to propagate in differentdirections. As shown in FIG. 1, the lasers 10 may emit laser beams andimpinging on the lens 20 (e.g., a convex lens). If the lens 20 is aconvex lens, the lens 20 may refract the incoming laser beams toward afocal point after which the laser beams may diverge. As shown, if thelasers are stacked in the vertical direction, the laser beams 29 mayalso diverge in the vertical direction. The beams 29 have a uniformangular distribution. That is, the beams 29 are spaced by a constantangular separation.

Conventional multiline Lidar though improves over the uniline Lidarstill has significant drawbacks. As described above, for thevehicle-based and other Lidar applications, the constant verticalangular resolution caused by constant angular distribution of laserbeams in the vertical field of view can be a source for deterioratingLidar performance. For example, laser beams emitted upwards are mostlywasted because the main targets for Lidar are more likely to be on thesame horizontal level as the Lidar-mounted vehicle, while insufficientlaser beams are dedicated in the horizontal level to detect the maintargets. Also for real applications, it is unpractical for currenttechnologies to build a Lidar with a reasonable number of lines and bothhigh vertical resolution and high scanning frequency. Further, theexisting multiline Lidar is disadvantaged for its high cost andsignificant packaging difficulty. Conventionally, each laser emits alaser beam, which corresponds to a laser emergence angle from the Lidar.Since deploying multiple lasers in the Lidar can increase the resolutionof the Lidar in the vertical direction, a laser (which is usuallyexpensive) needs to be disposed in correspondence to each emitting anglein the multiline Lidar, and consequently, the cost of the Lidarmultiplies. In addition, each laser of the multiline Lidar needs to beplaced at a fixed location within a limited space, making packagingrelatively difficult.

To at least mitigate the above-described technical problems, variousembodiments of Lidar systems and methods are disclosed. To make theforegoing objective, features, and advantages of the disclosed systemsand methods more comprehensible, various embodiments are described indetail below with reference to the accompanying drawings.

Referring to FIG. 2 to FIG. 16, FIG. 2 is a schematic view diagram of aLidar system 200, FIG. 3 is structural diagram of a rotor of a Lidarsystem, FIG. 9 is a schematic structural diagram of an emittingapparatus 120 in the Lidar system 200, and FIG. 10 is a schematicstructural diagram of a receiving apparatus 130 in the Lidar system 200.

Referring to FIG. 2, the Lidar 200 includes an emitting and receivingapparatus 110, which includes an emitting apparatus 120 and a receivingapparatus 130. In some embodiments, the Lidar 200 includes a fixingapparatus 100. The fixing apparatus 100 may be fixed, attached, orotherwise disposed on various objects, such as a vehicle. The Lidar 200may further include an optional rotation apparatus 140 connecting thefixing apparatus 100 to the emitting and receiving apparatus 110. Therotation apparatus 140 may comprise a rotating shaft 141 (drawn in dashline because it may not be apparent from the outside). The rotationapparatus 140 is configured to drive the emitting and receivingapparatus 110 to rotate about the rotating shaft 141.

In some embodiments, the Lidar 200 is mounted on a ground, and is fixedrelative to the ground. The rotating shaft 141 is perpendicular to ahorizontal plane as shown in FIG. 2 (the horizontal plane being a planeof rotation of the rotating shaft 141 in FIG. 2). In some embodiments,the Lidar may be mounted on an airplane or a vehicle, and an anglebetween a rotation plane of the rotating shaft 141 and a horizontalplane may be greater than zero.

In some embodiments, the rotation apparatus 140 drives the emitting andreceiving apparatus 110 to rotate around the rotating shaft 141, so thatthe emitting and receiving apparatus 110 can emit and receive beams indifferent directions, thereby increasing the field of view along ahorizontal direction and increasing the horizontal angular resolution ofthe Lidar.

In some embodiments, the Lidar does not comprise the rotation apparatus140, and the emitting and receiving apparatus 110 is fixedly disposed onthe fixing apparatus 100.

In some embodiments, when the Lidar is not rotating, the emittingapparatus 120 may emit laser beams which project into the environment toscan a line (e.g., a vertical line scan 77). Along this line scan 77, aplurality of laser beam spots may be non-uniformly distributed (e.g.,denser in the middle of the line scan 77 as discussed below). Thespacing between the laser beams spots along the line scan 77 maydetermine the angular resolution of the Lidar. When the Lidar rotates,the line scan 77 turns into a surface scan 78 (greyed area) as avertical area is scanned by the laser beams. In this example, theangular range of the line scan 77 or of the surface scan 78 in thevertical plane may determine the vertical field of view of the Lidar(that is, in some embodiments, the vertical field of view may be theangle between the two arrows shown in this figure), and the angularrange of the surface scan 78 in the horizontal plane may determine thehorizontal field of view of the Lidar. Correspondingly, the distributionof light beams along the vertical line may determine the resolution ofthe Lidar system in the vertical field of view, and the rotation speedof the Lidar may determine the resolution of the Lidar system in thehorizontal field of view. In some embodiments, a non-uniformdistribution of laser beams in the vertical field of view means that theemitted laser beams (e.g., emitted from the emitting apparatus 120 andwithin the same vertical plane) are distributed unevenly with respect tothe angular distribution of the beams within the vertical field of viewof the Lidar system.

In various embodiments, a Lidar system may comprise a rotor and a stator(e.g., in the emitting and receiving apparatus 110). For example, therotor may rotate about the rotating shaft 141. The rotor may compriseone or more supporting bodies vertically disposed in the rotor, and aplurality of lasers (e.g., corresponding to the emitting apparatus 120)disposed on each of the supporting bodies and configured to emit laserbeams respectively, wherein the lasers are distributed non-uniformlyalong a vertical direction from a highest to a lowest of the lasers(e.g., the concentration of the lasers first increases and thendecreases inside the rotor in a vertical direction from the highestlaser to the lowest laser). The rotor may further comprise a pluralityof detectors (e.g., corresponding to the receiving apparatus 130)configured to detect light reflected off a target, and the reflectedlight is a portion of the emitted laser beams reflected by the target.An exemplary overall structure of the rotor is shown in FIG. 3. Variouslaser and supporting body configurations are shown in FIG. 4A to FIG. 8.

FIG. 3 is a simplified structural diagram of a Lidar 192, consistentwith various embodiments of the present disclosure. FIG. 3 shows a topsectional view of a horizontal cross section of the Lidar 192, and thepositions of various components shown are merely exemplary. For example,components 1 and 5 and components 11 and 51 fixed upon the components 1and 5 may be disposed horizontally, vertically, or at another anglerelative to the Lidar.

In various embodiments, the exemplary Lidar 192 includes: a rotor 190and a stator 191 separated by an outer cavity 7. The rotor 190 mayrotate about the rotating shaft 141, that is, rotate with respect to thestator 191. As shown in FIG. 3, the rotor 190 includes an inner cavity8. The inner cavity 8 may be separated into an emitting cavity (theupper half of the inner cavity 8 above a separation board 91 in FIG. 3)and a receiving cavity (the lower half of the inner cavity 8 below theseparation board 91 in FIG. 3), for example, by using the separationboard 91. In the emitting cavity, a plurality of lasers 11 may bedisposed, and in the receiving cavity a plurality of detectors 51 may bedisposed. Various configurations of the lasers 11 and correspondingsupporting bodies 1 are described below with reference to FIG. 4A toFIG. 6.

Still referring to FIG. 3, in some embodiments, the rotor 190 mayfurther comprise a first reflector 61, a second reflector 62, and anoptical emitting device 2. The angle between the first reflector 61 andthe laser beams emitted by the lasers 11 may be an acute angle, that is,the first reflector 61 may be disposed obliquely relative to thesupporting body 1. The detection light (the laser beams emitted by thelasers until reaching a target) is sequentially reflected by the firstreflector 61 and the second reflector 62 and then passes through theoptical emitting device 2. The detection light emitted by the lasers 11may pass through the optical emitting device 2 (e.g., collimation lens,collimation lens assembly) and then irradiate on an external object 3.

In some embodiments, the rotor 190 may further comprise a lightfiltering device 6 (e.g., light filter). The light filtering device 6may be disposed outside the inner cavity 8 for filtering out ambientlight. The light filtering device 6 may be disposed on a light path ofreflected light off the external object 3 and may be located upstream ofan optical receiving device 4.

In some embodiments, the receiving cavity may comprise the opticalreceiving device 4 (e.g., focusing lens, focusing lens assembly), athird reflector 63, a fourth reflector 64, and a plurality of detectors51. The reflected light off the external object 3 passes through theoptical receiving device 4 and then is received by the detectors 51. Anangle between the third reflector 63 and the principal axis of theoptical receiving device 4 may be an acute angle. The reflected lightthat passes through the optical receiving device 4 may be sequentiallyreflected by the third reflector 63 and the fourth reflector 64, andthen is received by the detectors 51. The detectors 51 may be fixed on acircuit board 5 or an alternative structure. The quantity of thedetectors 51 may be the same as that of the lasers 11. The detectors maybe disposed symmetrical to the lasers about a mid-vertical plane of aline connecting the center of the optical collimation device to thecenter of the optical receiving device.

In some embodiments, the plurality of lasers 11 emit a plurality oflaser beams. For example, a No. 1 laser emits detection light, whichsequentially passes through a first reflector 61 and a second reflector62 and then is incident on an optical emitting device 2, and irradiateson an external object 3 after being collimated by the optical emittingdevice 2. Reflected light off the external object 3 converges afterpassing through the optical receiving device 4, and then is sequentiallyreflected by a third reflector 63 and a fourth reflector 64 ontodetectors 51. In summary, the detection light emitted by the No. 1 laseris reflected by the external object 3, passes through the opticalreceiving device, and then converges to a No. 1 detector.

In some embodiments, the detectors 51 may detect the reflected light asoptical signals, and correspondingly generate electrical signals basedon the detection. The Lidar may further comprise an analysis device (notshown) configured to processes the electrical signals generated by thedetector 51 to detect the external object 3, such as an obstacle.

In view of the description of FIG. 3, in some embodiments, the rotor maycomprise an emitting cavity for disposing the lasers and a receivingcavity for disposing the detectors. The emitting cavity and thereceiving cavity may be separated by a separation board. The emittedlaser beams may be reflected by a first and a second reflectors and passthrough an optical emitting device to exit the Lidar. The reflectedlight, after entering the Lidar, may pass through an optical receivingdevice and may be reflected by a third and a fourth reflectors reflectedby two reflectors to reach the detectors.

In some embodiments, the Lidar system comprises a rotor and a stator.The rotor is configured to rotate with respect to the stator. The rotorcomprises at least one supporting body and a plurality of light sourcesdisposed on the at least one supporting body, the plurality of lightsources configured to emit a plurality of first light beams. Theplurality of first light beams are non-uniformly distributed along avertical direction in a vertical field of view of the Lidar system. Inone example, the at least one supporting body comprise a plurality ofthe supporting bodies disposed non-uniformly along the verticaldirection in the vertical field of view of the Lidar, causing theplurality of first light beams to non-uniformly distribute along thevertical direction in the vertical field of view of the Lidar (referringto FIG. 5 and FIG. 6 below). The plurality of light sources comprise oneor more lasers disposed on each of the supporting bodies; and aconcentration of the lasers first increases and then decreases insidethe rotor along a vertical direction from a highest laser to a lowestlaser of the lasers. The non-uniform distribution of the plurality offirst light beams along the vertical direction comprises a sparserconcentration of the first light beams at each of two ends of thevertical field of view of the Lidar and a denser concentration of thefirst light beams towards center of the vertical field of view of theLidar. The Lidar system may further comprise: an optical splittingapparatus configured to split each of the first light beams into aplurality of third light beams with different propagation directions,wherein the third light beams are non-uniformly distributed along thevertical direction in the vertical field of view of the Lidar system.Various embodiments to achieve the nonuniform distribution of lightbeams (also be referred to as laser beams) are discussed below.

FIG. 4A is a simplified structural diagram of a structure 290 comprisinga supporting body and lasers of a Lidar, consistent with variousembodiments of the present disclosure. FIG. 4A illustrates exemplarycomponents that can be disposed in the emitting cavity. As shown in FIG.4A, a supporting body 1 is configured to support a plurality of lasers11. The plurality of lasers 11 may comprise, for example, twenty orforty lasers 11, where the quantity of the lasers 11 corresponds to thequantity of lines of the Lidar. In some embodiments, the lasers 11 arefixed on the supporting body 1 from top to bottom, and are collinear.Alternative to the supporting body, various other methods can be used toposition the lasers to achieve similar results.

In some embodiments, the projection points of beams from the lasers 11on a vertical plane 21 (including the principal axis of the opticalcollimation device) are distributed in a non-uniform density in avertical direction. That is, the collinear lasers 11 are verticallydistributed non-uniformly along the supporting body 1. For example, thelasers are distributed densely in the middle part of the supporting body1, and are distributed sparsely in the upper and lower parts of thesupporting body 1. In FIG. 4A, FIG. 5, and FIG. 6, laser beams can beassumed to emit along the dot-dash line directions by correspondinglasers, with intermediate optical and/or mechanical components omitted.The direction of the laser beam emission may also be referred to as an“emission direction.” When the emission directions of the emitted beamsare parallel, the emission direction is the same for all of the lasers.For example, when the emission direction is the horizontal direction,the vertical direction can be referred to a distribution directionnormal to the emission direction, and the laser may be distributednon-uniformly along the distribution direction. In the verticaldirection, the concentration of lasers may correspond to theconcentration of emitted laser beams, which is non-uniform (e.g., densein the middle of the overall structure in the vertical direction).Various other modifications to the laser positions can also be included(e.g., by adding optical or mechanical light path manipulation) as longas the lasers are distributed non-uniformly in the direction thatcorresponds the Lidar line scan (before the Lidar rotates) andcontribute a non-uniform laser beam spot distribution along the Lidar'sline scan. For example, a denser laser distribution towards the middleof the distribution direction contributes to a denser laser beam spotdistribution towards the middle of the line scan.

In some embodiments, the plurality of lasers 11 emit a plurality oflaser beams. For example, a No. 1 laser emits a detection beam, which iscollimated by an optical collimation device and then irradiates towardsan external object. Since the density of central laser beams is high(referring to the “dense” part of laser beams in FIG. 4A), the Lidar'svertical angular resolution can be improved. If the supporting body 1 isdisposed vertically on a vehicle, the angular resolution in a rangeincluding a horizontal plane close to the ground and near the horizontalplane can be improved.

In some embodiments, the Lidar may further comprise an opticalcollimation device (e.g., optical emitting device 2) such as acollimation lens disposed in the emitting cavity. The beams emitted bythe lasers 11 pass through the optical collimation device and thenirradiate on an external object, for example, a ground, a pedestrian, abicycle, a bus stop board, or an automobile.

In some embodiments, the Lidar may further comprise an optical receivingdevice (e.g., optical receiving device 4) such as a focusing lens(assembly) and a plurality of detectors disposed in the receivingcavity. Reflected light off an external object passes through theoptical receiving device and then is received by the detectors. Thequantity of the detectors may be the same as that of the lasers 11. Thedetectors may be disposed symmetrical to the lasers about a mid-verticalplane of a line connecting the center of the optical collimation deviceto the center of the optical receiving device.

In some embodiments, the plurality of lasers 11 are not all collinear.For example, some (e.g., a larger portion) of the lasers 11 in group 1are vertically disposed at equal intervals and are collinear, and theremaining lasers in group 2 are vertically disposed at equal intervalsand are collinear. The group 1 and group 2 may be on the same supportbody or different supporting bodies. The group 1 in a first verticalplane is horizontally displaced from the group 2 in a second verticalplane. The first and second vertical planes may be parallel and close toeach other. For example, the Lidar may comprise a laser structure 299including sixteen lasers as shown in FIG. 4B, which is a simplifiedstructural diagram of a structure comprising a supporting body andlasers of a Lidar, consistent with various embodiments of the presentdisclosure. That is, the Lidar is a 16-line Lidar. The sixteen lasersare disposed in two columns on one supporting body and are located onthe focal plane of an optical collimation device. In Column 1, No. 1 toNo. 10 lasers are vertically disposed at equal intervals and arecollinear. In Column 2, No. 11 to No. 16 lasers are vertically disposedat equal intervals and are collinear. The intervals between neighboringlasers in each column are respectively d. Column 2 is disposed parallelto and on one side of Column 1. The distance from the No. 11 laser inColumn 2 to the No. 3 laser in Column 1 is equal to the distance fromthe No. 11 laser in Column 2 to the No. 4 laser in Column 1. Thedistance from the No. 16 laser in Column 2 to the No. 8 laser in Column1 is equal to the distance from the No. 16 laser in Column 2 to the No.9 laser in Column 1. That is, in the vertical direction, the No. 11laser is between the No. 3 and No. 4 laser, and the No. 16 laser isbetween the No. 8 and No. 9 lasers. Accordingly, in the verticaldirection, the interval is d between the No. 1 and the No. 2 lasers,between the No. 2 and the No. 3 lasers, and between the No. 9 and theNo. 10 lasers respectively. Also in the vertical direction, the intervalis d/2 between the No. 3 and No. 11 lasers, between the No. 11 and theNo. 4 lasers, between the No. 4 and the No. 12 lasers, between the No.12 and the No. 5 lasers, between the No. 5 and the No. 13 lasers,between the No. 13 and the No. 6 lasers, between the No. 6 and the No.14 lasers, between the No. 14 and the No. 7 lasers, between the No. 7and the No. 15 lasers, between the No. 15 and the No. 8 lasers, betweenthe No. 8 and the No. 16 lasers, and between the No. 16 and the No. 9lasers respectively. Since the lasers may emit beams out of the plane ofthe paper, the beams are denser toward the middle of the supporting bodyin the vertical direction. Thus, the above exemplary structure of twocolumn lasers can substitute the structure 290 described above toachieve a non-uniform distribution of beams.

In view of the description of FIG. 4A and FIG. 4B, in some embodiments,the rotor may comprise only one supporting body. The plurality of lasersmay be disposed on the only one supporting body. The concentration ofthe lasers first may increase and then decrease in a vertical directionfrom top to bottom of the one supporting body.

Examples of multiple supporting bodies are described below withreference to FIG. 5 and FIG. 6, in which the intermediate optics of theLidar are not shown and Lidar detection beams are represented bystraight lines from lasers towards an imaginary plane where targets maybe found. The group 1 laser beams may project points evenly in avertical direction, and the group 2 lasers may be positioned such thatprojection points from the group 2 lasers crisscross with a portion ofthe projection points from the group 1 lasers. Thus, the crisscrossedregion has a higher density of beams and thus a higher vertical angularresolution, which can be configured in the horizontal direction and nearthe horizontal direction. In some embodiments, the distribution of thelight beams along a vertical direction of the Lidar system may beadjusted by configuring the position of the supporting bodies.

FIG. 5 is a simplified structural diagram of a structure 390 comprisinga plurality of supporting bodies and lasers in an emitting cavity of aLidar, consistent with various embodiments of the present disclosure. Insome embodiments, the emitting cavity may comprise a plurality ofsupporting bodies 1 and a plurality of lasers 11 on each of thesupporting bodies 1. For example, the structure 390 may comprise fivesupporting bodies 1, where each supporting body is vertically fixed inthe emitting cavity for supporting the plurality of lasers, and theplurality of supporting bodies 1 are distributed at various intervals ina horizontal direction. For example, in some embodiments, in an (x, y,z) coordinate system, the supporting bodies may be disposed vertically(along the z direction) at various z positions, and the (x, y) plane isa horizontal plane. The supporting bodies may be disposed at the same xposition but different y positions, and the “various intervals in thehorizontal direction” may refer to intervals among the lasers in they-direction. The lasers on the supporting bodies may aim toward thex-direction, and the emitted beams may propagate in the x-direction.

In some embodiments, the plurality of lasers 11 may comprise, forexample, forty lasers 11, where the quantity of the lasers 11corresponds to the quantity of lines of the Lidar. The lasers may befixed on the supporting bodies from top to bottom. The lasers on theeach supporting body may be collinear.

In some embodiments, the structure 390 may further comprise opticalcollimation devices (not shown in FIG. 5) such as collimation lenses.The projection points of the lasers 11 on a vertical plane 21 (e.g., animaginary plane) are distributed in a non-uniform density in a verticaldirection. The vertical plane 21 is associated with principal axes(shown as dot-dash lines) of the optical collimation devices. Forexample, as shown in the vertical direction, the lasers andcorresponding laser beams or laser lines are distributed densely in themiddle part of the structure 390, and are distributed sparsely in theupper and lower parts. At the vertical plane 21, between laser beamsfrom neighboring lasers on the leftmost supporting body, there is atleast one laser beam from a laser on another supporting body. As shown,two laser beams from different supporting bodies are present betweenevery two beams from neighboring lasers on the leftmost supporting bodyat the vertical plane 21. Thus, the laser beam concentration in thevertical direction increases accordingly where the lasers are dense. Forthe lasers to not block each other, in the y-direction, the supportingbodies may be displaced from one another. Such displacement may besmall, such that the laser beams are unblocked and the lasers can stillbe considered as in the same vertical plane.

Correspondingly in the vertical direction, the emitted beams may bedense in the middle part and sparse in the upper and lower parts. Beamsemitted by the lasers may pass through the optical collimation devicesrespectively and then irradiate on an external object, for example, aground, a pedestrian, a bicycle, a bus stop board, or an automobile. Asthe Lidar rotates, the vertical line of non-uniformly distributed beamscan scan a vertical area ahead, where the middle strip of the verticalarea has denser beams for detection and thus has an increased detectionaccuracy. Since the external object is usually at the same horizontallevel as the Lidar, the external object is more likely to be detected bybeams in the middle strip, and can afford more accurate detection.

In view of the description of FIG. 5, in some embodiments, the rotor maycomprise at least two supporting bodies, and at least two of the lasersare disposed on each of the at least two supporting bodies andconfigured to emit laser beams correspondingly in at least two verticalplanes. For example, the rotor may comprise four supporting bodies, andfour of the lasers may be disposed and evenly-spaced on each of thesupporting bodies.

FIG. 6 is a simplified structural diagram of a structure 490 comprisinga plurality of supporting bodies and lasers in an emitting cavity of aLidar, consistent with various embodiments of the present disclosure.The structure 490 may be an alternative structure of the structure 290or 390 to implement in an emitting cavity of a Lidar. As shown in FIG.6, the structure 390 may comprise a plurality of fixing plates 12, aplurality of supporting bodies 1, and a plurality of lasers 11 attachedto each of the supporting bodies 1. For example, the structure 390 maycomprise eight supporting bodies 1 on five fixing plates 12, and fiveevenly-spaced lasers 11 may attach to each supporting body 1.

For example, as shown in FIG. 6, five fixing plates 12 are verticallydisposed in the emitting cavity, and are separated in a horizontaldirection (e.g., y-direction). One or more supporting bodies 1 are fixedon a side of the each fixing plate 12. The number of supporting bodies 1fixed on the each fixing plates 12 may vary. For example, as shown inFIG. 6 from left to right, the number of the supporting bodies fixed onthe fixing plates are respectively two, one, two, two, and one.

In some embodiments, the supporting bodies 1 are fixed to variouspositions on the fixing plates 12, such that the overall concentrationof lasers is denser in the middle part of the structure 490 along thevertical direction. As shown in FIG. 6, projection points (representingbeams) of the lasers 11 are distributed non-uniformly in a verticaldirection on a vertical plane 21. For example, in the verticaldirection, the lasers and corresponding laser beams or laser lines aredistributed densely in the middle part of the structure 490, and aredistributed sparsely in the upper and lower parts. At the vertical plane21, between laser beams from neighboring lasers on the leftmostsupporting body, there is at least one laser beam from a laser onanother supporting body. As shown, two laser beams from differentsupporting bodies are present between every two beams from mostneighboring lasers on the leftmost supporting body at the vertical plane21. For example, between laser beams emitted by lasers 45 and 48disposed on the leftmost supporting body, laser beams emitted by lasers46 and 47 disposed on some other supporting bodies are found. Thus, ifthe laser beams emitted by lasers 45 and 48 are separated by distance d,the laser beams emitted by lasers 45, 46, 47, and 48 are spaced at d/3apart in the vertical direction. Thus, the laser beam concentration inthe vertical direction increases accordingly where the lasers are dense.For example, in the vertical direction, if neighboring lasers on eachindividual supporting body are separated by d, the laser beams aredistributed densely in the middle part of the structure 490 byconfiguring the arrangement of the lasers on the various supportingbodies as shown in FIG. 6. Viewing from another perspective into theplane of laser beam emission, an exemplary corresponding structure 690is shown in FIG. 8 described below. Correspondingly, the laser beams aredistributed densely in the middle part of the structure 690 whereintervals between neighboring laser beams are each d/3, and aredistributed sparsely in the upper and lower parts of the structure 690where intervals between neighboring laser beams are each d. For thelasers to not block each other, in the y-direction, the supportingbodies may be displaced from one another. Such displacement may besmall, such that the laser beams are unblocked and the lasers can stillbe considered as in the same vertical plane.

Correspondingly in the vertical direction, the emitted beams may bedense in the middle part and sparse in the upper and lower parts. As theLidar rotates, the vertical line of non-uniformly distributed beams canscan a vertical area ahead, where the middle strip of the vertical areahas denser beams for detection and thus increased detection accuracy.Since the external object is usually at the same horizontal level as theLidar, the external object is more likely to be detected by beams in themiddle strip, and can afford more accurate detection.

In some embodiments, the vertical field of view range of a 40-linein-vehicle Lidar is −14° to +5° (the horizontal level is 0°). In therange of 3° to 5°, the vertical angular resolution is 1° (correspondingto laser beams of the 1st to 3rd lines from bottom to top in FIG. 6).The range of −7° to 3° is a densified subdivision section, and thevertical angular resolution is ⅓° (corresponding to laser beams of the3rd to 33rd lines from bottom to top in FIG. 6). In the range of −14° to−7°, the vertical angular resolution is 1° (corresponding to laser beamsof the 33rd to 40th lines from bottom to top in FIG. 6). That is, insome embodiments, the Lidar has a vertical field of view range of +5° to−14° corresponding to a span of the emitted beams from the verticallylowest laser to the highest laser, with the horizontal level being 0°.In the vertical field of view range of +5° to +3°, the Lidar has avertical angular resolution of 1° corresponding to a first concentrationof laser beams. In the vertical field of view range of 3° to −7°, theLidar has a vertical angular resolution of ⅓° corresponding to a secondconcentration of laser beams. In the vertical field of view range of −7°to −14°, the Lidar has a vertical angular resolution of 1° correspondingto a third concentration of laser beams. The second concentration ishigher than the first concentration and third concentration of laserbeams.

In view of the description of FIG. 6, in some embodiments, the rotor maycomprise five vertically disposed fixing plates, two of the supportingbodies may be disposed on each of three of the five fixing plates, oneof the supporting bodies may be disposed on each of two of the fivefixing plates, and four lasers may be disposed on each of the supportingbodies.

FIG. 7 is a simplified structural diagram of a scanning apparatus 590 inthe Lidar, consistent with various embodiments of the presentdisclosure. The rotor 190 described above may be implemented in thescanning apparatus 590 for target detection. For example, the rotor 190when stationary can detect signals from a vertical line, and when therotor 190 is rotated by the scanning apparatus 590, the vertical lineturns into an area in which targets can be detected. As shown in FIG. 7,the scanning apparatus 590 may include: a central shaft 92, a fixingseat 97, a motor 94, a coupling 95, a rotation cavity 96, and a base 93.In some embodiments, the central shaft 92 is provided with a groove, andis divided into a thick part, a transitional part, and a fine part frombottom to top. A top end of the central shaft 92 is fixed on the fixingseat 97. For example, the fixing seat 97 is a circular groove of whichthe center is provided with a protrusion, and a top end of the fine partof the central shaft 92 is fixed on the protrusion. The motor 94 isdisposed on a lower part of the fixing seat 97 and is adjacent to thefixing seat 97. A stator of the motor 94 is sleeved on an outer edge ofthe fine part of the central shaft 92 located between the fixing seat 97and the base 93. For example, the stator of the motor 94 is sleeved onan outer edge of the fine part of the central shaft 92. A rotor of themotor 94 rotates around the central shaft 92, and a power cable of themotor 94 is laid in the groove. A bottom end of the rotor is connectedto a rotation cavity by using the coupling 95, so that the rotor of themotor 94 drives the rotation cavity to rotate around the central shaft92. The rotation cavity 96 may correspond to the rotor 190 describedabove. The rotation cavity 96 is fixed, by using a bearing, on an outeredge of the central shaft 92 located on a lower part of the stator. Forexample, the rotation cavity 96 is fixed on an outer edge of thetransitional part of the central shaft 92. The rotation cavity 96 isdistributed on a lower part of the motor 94 and on the periphery of themotor 94, along a radial direction of the central shaft 92, rather thanon an upper part of the motor 94. The inside of the rotation cavity 96can be separated into an emitting cavity and a receiving cavitydescribed above. The bottom end of the central shaft 92 is fixed on thebase 93. For example, the base 93 is a circular groove of which thecenter is provided with a protrusion, and the thick part of the centralshaft 92 is fixed on the protrusion of the base.

As shown in FIG. 7, the scanning apparatus 590 may further include awireless power transmission module. The wireless power transmissionmodule may include: a transmitting part, a receiving part 71, an uppercircuit board 72, a lower circuit board 73, and a rotary encoder 74. Thetransmitting part may be fixed on the central shaft 92. The receivingpart 71 may be fixedly connected to the rotation cavity 96, and rotatingaround the central shaft 92. The upper circuit board 72 may be disposedon a bottom end of the rotation cavity 96, where the wireless powertransmission module supplies power to the upper circuit board 72. Thelower circuit board 73 may be fixed on the base 93, where the distancebetween the upper circuit board 72 and the lower circuit board 73 isgreater than zero. The rotary encoder 74 may be disposed on the bottomend of the rotation cavity 96, where the distance between the rotaryencoder 74 and the base 93 is greater than zero. In some embodiments,the motor 94 is rotatably fixed on an outer edge of the fine part of thecentral shaft 92, so that the distance between upper and lower circuitboards is short, thereby facilitating communication and simplifyingmaintenance of the transmission system.

FIG. 8 is a simplified structural diagram of a structure 690 comprisinga plurality of supporting bodies and lasers in a Lidar, consistent withvarious embodiments of the present disclosure. In some embodiments, theLidar may comprise forty lasers. That is, the Lidar is a 40-line Lidar.The Lidar may comprise eight supporting bodies and five fixing plates 12that are vertically disposed in the z-direction, as described above withreference to FIG. 6. As shown in FIG. 8, the fixing plate 12 can each bedisposed in a groove 81 in a vertical direction and fixed by using anadhesive 82. Along fixing plates in the y-direction, the quantities ofthe supporting bodies disposed on the fixing plates are respectively 2,1, 2, 2, and 1 (not shown). Five lasers can be disposed on eachsupporting body in a vertically collinear manner at an interval of dbetween neighboring lasers on the same supporting body. That is, thestructure 490 may be inserted into the grooves and fixed with respect tothe groove by the adhesive to obtain the structure in FIG. 8. Thus,coaxial transmission (that is, the motor, rotation cavity, upper circuitboard, and the like all rotate around a central shaft) can beimplemented in Lidar, so that the number of transmission parts and theoccupied space are greatly reduced, thereby improving the systemstability.

As described, the disclosed systems and methods can mitigate or overcomedeficiencies in the existing technologies. The disclosed Lidar maycomprise a plurality of non-uniformly distributed lasers in the verticaldirection. The disclosed Lidar has a high vertical angular resolution, ahigh horizontal angular resolution, a high scanning rate, and anaccurate scanning performance without requiring an excessive number oflaser lines. The above-described structures form FIG. 4A to FIG. 6 caneach achieve the non-uniform distribution of beams. For in-vehicleLidars, by increasing the density of central laser beams (at thehorizontal level and near the horizontal), distant pedestrians,vehicles, and the like that more likely appear at such elevation can bedetected more accurately.

In some embodiments, lasers in the Lidar can be disposed non-uniformlyalong the vertical direction, so that laser beams are non-uniformlydistributed in the vertical direction. Thus, with a relatively smallnumber of beams, a relatively high vertical angular resolution can beachieved at a low cost, and the Lidar size can be reduced.

In some embodiments, various targets (e.g., pedestrians, vehicles,obstacles) that need to be detected by a smart vehicle usually appear ona horizontal level (e.g., at the ground level) with respect to the smartvehicle. Therefore, enhancing the density of central laser beams at thehorizontal and near the horizontal level for the Lidar mounted on thesmart vehicle is necessary for a real-world traffic environment toensure safety, reliability, and performance of the smart vehicle.

Alternative or additional to the optical methods, various mechanicalmethods can be used to achieve the non-uniform distribution of beams, asdescribed below with reference to FIG. 9 to FIG. 16.

Referring to FIG. 9 and FIG. 10, FIG. 9 illustrates laser beam emissionfrom a Lidar system, and FIG. 10 illustrates receiving reflected beamsby the Lidar system. The emitted laser beams may be reflected by atarget to form the reflected beams, so that the target can be detectedby the Lidar.

Referring to FIG. 9, the emitting apparatus 120 includes a laser 121(e.g., a solid-state laser, an optical fiber laser) configured togenerate and emit a laser beam 111 in an emission direction towards atarget, and an optical splitting apparatus 123 configured to split thelaser beam 111 into a plurality of laser beams 222 propagating alongdifferent directions. The laser beams 222 propagating along differentdirections, when reflected back, can be used for detecting targetslocated in different directions. Thus, the diverging laser beams 222 canincrease the field of view and the angular resolution of the Lidar.Moreover, the optical splitting apparatus 123 can produce the pluralityof laser beams 222 from one laser source, thereby conserving lasersusage and reducing the cost and the packaging difficulty of the Lidar.The beams 222 may be non-uniformly distributed. For example, in thevertical direction and past the optical splitting apparatus 123, thebeams 222 may be more concentrated towards the optical axis 89, andsparser away from the optical axis 89. The targets fall in theconcentrated beam area (e.g., those located at the same level as thelaser) can afford a higher detection accuracy without having to deploymultiple lasers. This advantage overcomes the weakness in currentvehicle-mounted Lidar technologies where targets are mostly at the sameheight range with the vehicle to maximize the laser utilization andaccuracy. Though only one laser is shown in FIG. 9, multiple lasers canbe used, and FIG. 12 described later shows two lasers in the emittingapparatus.

In some embodiments, an angle between the laser beam 111 and therotating shaft 141 is greater than zero.

In some embodiments, the wavelength of the laser beam 111 is between 895nm and 915 nm (e.g., 905 nm). This wavelength range corresponds toinfrared light which are invisible and penetrative, which can improvethe detection range of the Lidar and prevent disturbance to theenvironment. In some embodiments, the wavelength of the laser beam 111may be another value.

In some embodiments, the optical splitting apparatus 123 comprises adiffraction grating, which conforms with the principle: where that dsin(η)=mλ, d being the grating period, m being the diffraction order, λbeing the wavelength, and θ is the angle between the laser beam 222 andthe optical axis 89. When the angle θ is small, the sine function valueof the angle is close to the corresponding angle value. When the angleis small, the sine function value of the angle is smaller than thecorresponding angle value. As the angle increases, the larger thedifference between sin(θ) and θ becomes. Therefore, when the diffractionorder m is small, the angle θ is small (closer to the optical axis 89)and proportionate to the diffraction order m. When the diffraction orderm is large, the angle θ is large (e.g., larger than sin(θ), away fromthe optical axis 89), the beams spread out more. Thus, the abovenon-uniform beam distribution can be obtained.

In some embodiments, the optical splitting apparatus 123 comprises aDammann grating. The Dammann grating may split the laser beam 111 intothe plurality of laser beams 222 of equal intensities. Thus, situationsof failing to detect a particular target due to an excessively low lightintensity can be prevented, and the performance of the Lidar can beimproved. In some embodiments, the optical splitting apparatus mayalternatively be an optical fiber beam splitter, a plane diffractiongrating, a blazed grating, a lens combination etc. The optical splittingapparatus 123 can also be an optical system comprising a plurality ofoptical elements (such as a lens, a spectroscope and the like). Theoptical splitting apparatus 123 can be configured to refract, reflect,diffract, or interfere light, causing an impinging laser beam is to bedivided into a plurality of split laser beams with different propagationdirections. The plane diffraction grating and the blazed grating mayeach comprise a one-dimensional grating.

In some embodiments, the optical splitting apparatus 123 comprises aone-dimensional Dammann grating. The manufacturing cost of theone-dimensional Dammann grating is low, so that the cost of the Lidarcan be reduced.

Alternatively, the optical splitting apparatus may comprise atwo-dimensional Dammann grating. The two-dimensional Dammann grating canproduce laser beams of various horizontal emitting angles and verticalemitting angles, thereby increasing the vertical angular resolution andthe horizontal angular resolution of the Lidar. The horizontal directionis a direction parallel to the horizontal plane, and the verticaldirection is a direction perpendicular to the horizontal plane.

For example, the Dammann grating may be a Dammann grating with 1×5 splitbeams, 1×9 split beams, 1×15 split beam, 1×32 split beams, 1×64 splitbeams, etc. More split beams of the Dammann grating indicate a largerangle of view and a higher resolution of the Lidar.

In some embodiments, the Dammann grating comprises a Dammann gratingwith 1×9 split beams. The optical splitting apparatus is aone-dimensional Dammann grating with 1×9 split beams. Phase transitionpoints of the optical splitting apparatus are 0.06668, 0.12871, 0.28589,0.45666, and 0.59090. The period d of the Dammann grating is 47 μm to 57μm (e.g., 52 μm).

In some embodiments, the plurality of laser beams 222 propagate indifferent angles with respect to the rotating shaft 141, therebyincreasing the angular resolution and the field of view of the Lidar.The laser beams 222 may emerge from the emitting apparatus 120 andpropagate in a plane. The plane may be in any direction depending thepositioning of the emitting apparatus 120 and/or optical arrangement.For example, the plane may be parallel to the plane of rotation of therotating shaft 141 such that the plurality of laser beams 222 propagatein the same angle with respect to the rotating shaft 141. In thisexample, the angular resolution and field of view in a horizontaldirection is increased. For another example, the plane may be a verticalplane such that the plurality of laser beams 222 propagate in differentangles with respect to the rotating shaft 141. In this example, theangular resolution and field of view in a vertical direction isincreased.

The Dammann grating is a binary phase Fourier beam splitting gratingwith unequal spacings and repeated periods. In some embodiments, theDammann grating includes a plurality of first areas and second areasthat are alternately arranged. The phase delay in the first area is a 0radian, and the phase delay in the second area is 7 radian. The firstarea and the second area are both elongated. A distance between adjacentfirst areas is the period of the Dammann grating. The widths of theplurality of first areas of the Dammann grating are different, and thewidths of the plurality of second areas of the Dammann grating aredifferent. By appropriately designing the period of the grating, thewidths of the first areas, and the widths of the second areas of theDammann grating, in some embodiments, the light intensities of thegenerated plurality of laser beams 222 are equal. In some embodiments,extension directions of the first areas and the second areas in theoptical splitting apparatus 123 are parallel to the rotating shaft 141,so that the angles between the laser beams 222 and the rotating shaft141 are different. Thus, if the rotating shaft 141 is perpendicular to ahorizontal plane, the vertical angular resolution of the Lidar apparatuscan be increased.

The Dammann grating can split, according to the diffraction principle,the laser beam 111 into the plurality of laser beams 222 of differentorders. Applying the formula of diffractive grating d sin θ=mλ to aDammann grating having N (e.g., N is an odd number) split beams, m cancomprise −(m−1)/2, −(m−1)/2+1, . . . , 0, . . . , (m−1)/2−1, (m−1)/2,and θ is an angle between the laser beam 222 and the normal of theDammann grating. When the wavelength of the laser beam 111 is constant,and the parameters of the Dammann grating are determined, angles betweenlaser beams 222 of different orders and the normal of the grating aredifferent, so that the plurality of laser beams 222 propagating alongdifferent directions can be obtained.

In some embodiments, the Lidar apparatus further includes: a beamexpanding and collimating apparatus 122 (e.g., a telescope) configuredto: increase the spot diameter of the laser beam 111 and reduce thedivergence angle of the laser beam 111. The beam expanding andcollimating apparatus 122 can increase the spot diameter of the laserbeam 111, thereby facilitating receiving, by using the receivingapparatus 130, the echo beams 333. The beam expanding and collimatingapparatus 122 can further reduce the divergence angle of the laser beam111, so as to accurately control a propagation direction of the laserbeam 111, thereby increasing the detection accuracy of the Lidar.

Referring to FIG. 10, in some embodiments, the receiving apparatus 130includes a plurality of detectors 131 and an analysis apparatus (notshown). Each detector 131 (e.g., a photodiode, a photomultiplier) isconfigured to: receive the echo beams 333 which come from the laserbeams 222 reflected by the target, and convert optical detection signalsinto an electrical signals. The analysis apparatus is configured toanalyze the electrical signal to obtain information (e.g., location) ofthe target.

In some embodiments, the receiving apparatus 130 further includes: asecond converging lens 132 configured to converge the echo beams 333 tothe detectors 131. Each corresponding pair of light beams incident onand leaving the converging lens 132 are represented by the same linetype and distinct from other pairs (e.g., solid line pairs, dash linepairs, dot-dash line pairs, etc.). A distance from the detectors 131 tothe focal plane of the second converging lens 132 may be less than halfof the focal depth of the second converging lens 132. In someembodiments, the detectors 131 are located at the focal plane of thesecond converging lens 132.

As shown in FIG. 10, echo beams that are reflected from laser beams withthe same propagation directions converge to a surface of the samedetector after passing through the second converging lens 132. Echobeams that are reflected from laser beams with different propagationdirections converge to different detectors after passing through thesecond converging lens 132. Accordingly, propagation directions of theecho beams 333 can be determined based on the detection signals by eachof the detectors, thereby determining the direction of the target.

In some embodiments, the receiving apparatus 130 is separated from theemitting apparatus 120, so that the echo beams 333 do not pass throughthe optical splitting apparatus 123. Thus, the optical splittingapparatus 123 can be prevented from changing the propagation directionsof the echo beams 333, to ensure accurate determination of the locationof the target.

FIG. 11A is a schematic structural diagram of an optical splittingapparatus 123 of a Lidar, consistent with various embodiments of thepresent disclosure. Various other components of the Lidar are not shown.The optical splitting apparatus 123 may be configured to rotate aboutthe optical axis 89. For example, a motor can couple to and rotate theoptical splitting apparatus 123.

The rotation of the optical splitting apparatus 123 can cause the laserbeams 222 to change in propagation directions, to effectuate adjustmentof the angular resolution. Further, the rotation of the opticalsplitting apparatus 123 can reduce overlapping among the laser beams222, thereby increasing the angular resolution. Thus, the rotation ofthe optical splitting apparatus 123 can balance between high angularresolution and the large field of view to help improve the detectionprecision and accuracy of the Lidar.

As shown, the optical splitting apparatus 123 may comprise atwo-dimensional grating (e.g., a two-dimensional Dammann grating) ofperiod d1 by d2. That is, the two-dimensional grating may compriselattice grids of width d1 by d2. The two-dimensional grating can splitthe laser beam 111 into the laser beams 222 of equal (or different)intensities. Accordingly, the emergence angle of the laser beams 222 isrelated to the wavelength A and the parameters of the optical splittingapparatus 123. For example, the wavelength A ranges from 95 nm to 915 nm(e.g., 905 nm), and d1 and d2 are each is in the range of 47 μm to 57 μm(e.g., 52 μm).

As shown in FIG. 11A, an x-y-z coordinate system can be established withrespect to the grating plane of the optical splitting apparatus 123, andthe normal direction of the grating plane is the z direction. The zdirection is parallel to the optical axis 89. In some embodiments, theLidar is installed on the ground, the optical axis 89 is parallel to thehorizontal plane, so that the y direction is perpendicular to thehorizontal plane, the x direction is parallel to the horizontal plane.That is, the plane determined in the x direction and the z direction isparallel to the horizontal plane. In addition, the adjusting axis of theoptical splitting apparatus 123 is parallel to the optical axis 89, sothat the z axis is parallel to the adjusting shaft, and the rotation ofthe optical splitting apparatus 123 around the adjusting shaft is in thex-y plane.

If treating the first laser beam as a plane wave, the laser beams 222(only considering the phase in the propagation direction) can beexpressed as:

E=exp(j(k _(x) +k _(y) y+k _(Z) z))

As shown in FIG. 11A, when one side of the grating plane and the ydirection are parallel:

$k_{x} = {n_{x}\frac{2\pi}{d_{2}}}$$k_{y} = {n_{y}\frac{2\pi}{d_{1}}}$$k_{z} = \sqrt{k^{2} - k_{x}^{2} - k_{y}^{2}}$

In the formulas, d1 is the first grating period, d2 is the secondgrating period (notwithstanding the examples disclosed herein, thedescriptions of the grating plane in the d1 and d2 directions may beinterchangeable), and n_(x) and n_(y) represent the diffraction ordersin the x-direction and the y-direction respectively. According to thediffraction grating formula, the angle between the propagation directionof the laser beam 222 and the normal line of the grating is:

$\theta_{y} = {{\arcsin \left( \frac{k_{y}}{k} \right)} = {\arcsin \left( {n_{y}\frac{\lambda}{d_{1}}} \right)}}$

According to above formula, different diffraction orders n_(y)correspond to different angles between each two adjacent second laserbeams. Since d1 is far larger than the wavelength of the laser beam,angles between adjacent laser beams with different diffraction ordersn_(y) in the y direction are similar. Thus, the light spots formed bythe laser beams 222 on a vertical plane appears like a matrix.

FIGS. 11B-11C are graphical diagrams of light spots formed on a plane bylaser beams 222 of a Lidar, consistent with various embodiments of thepresent disclosure. In FIG. 11B, one side of the grating plane isparallel to the x direction, and the other side is parallel to the ydirection. In FIG. 11C, the grating plane rotate around the z directionby angle φ from the position in FIG. 11B. For FIG. 11C, the laser beams222 (only considering the phase in the propagation direction) can beexpressed as:

E = exp (j(k_(x)x + k_(y)y + k_(z)z)), where$k_{x} = {{n_{x}\frac{2\pi}{d_{2}}\cos \; \phi} + {n_{y}\frac{2\pi}{d_{1}}\sin \; \phi}}$$k_{y} = {{n_{x}\frac{2\pi}{d_{2}}\sin \; \phi} + {n_{y}\frac{2\pi}{d_{1}}\cos \; \phi}}$$k_{z} = \sqrt{k^{2} - k_{x}^{2} - k_{y}^{2}}$

According to the diffraction grating formula, the angle between thepropagation direction of the laser beam 222 and the normal line of thegrating is:

$\theta_{y} = {{\arcsin \left( \frac{k_{y}}{k} \right)} = {\arcsin \left( {{n_{y}\frac{\lambda}{d_{1}}\cos \mspace{14mu} \phi} + {n_{x}\frac{\lambda}{d_{2}}\sin \mspace{14mu} \phi}} \right)}}$

The light spots formed by the laser beams 222 on the plane are still ina matrix arrangement, which rotates along with the rotation of theoptical splitting apparatus 123.

As shown in FIGS. 11B-11C, the light spots in the x direction arestaggered along by the rotation of the optical splitting apparatus 123,and each light spot on the target plane corresponds to one of the laserbeams 222. The distance between the adjacent light spots in the ydirection increases with the angle between the corresponding laser beam222 and the horizontal plane. The number of the laser beams 222 withdifferent angles with the horizontal plane increases with the verticalangular resolution of the Lidar. Therefore, the rotation of the opticalsplitting apparatus 123 from the configuration in FIG. 11B to theconfiguration in FIG. 11C can cause more laser beams 222 havingdifferent angles with the horizontal plane and accordingly increase thevertical resolution of the Lidar.

In some embodiments, the optical splitting apparatus 123 may comprise atwo-dimensional Dammann grating with m by n beam splitting, m is thenumber of the laser beams in the d1 direction (one side of thetwo-dimensional grating), and n is the number of the laser beams formedin the d2 direction (the other side of the two-dimensional grating).

According to the grating equation, the acute angle φ between the d1direction and the y direction can be obtained as:

$\arctan \left( \frac{\arcsin \left( \frac{\lambda}{d_{1}} \right)}{m \times {\arcsin \left\lbrack \frac{\lambda}{d_{2}} \right\rbrack}} \right)$

In some embodiments, when the angle φ is in the range of:

$0.9\mspace{14mu} {\arctan \left( \frac{\arcsin \left( \frac{\lambda}{d_{1}} \right)}{m \times {\arcsin \left\lbrack \frac{\lambda}{d_{2}} \right\rbrack}} \right)}\mspace{14mu} {to}\mspace{14mu} 1.1{\arctan \left( \frac{\arcsin \left( \frac{\lambda}{d_{1}} \right)}{m \times {\arcsin \left\lbrack \frac{\lambda}{d_{2}} \right\rbrack}} \right)}$

By this configuration, the beam spots can be caused to distribute atmore vertical positions (y-positions), and thus the angular resolutionof the Lidar can be increased

In one example, the optical splitting apparatus 123 is 32 by 32 beamsplitting, the grating periods d1 and d2 are 52 μm, the wavelength ofthe laser beam is 905 nm. In the y direction, the field of view of theLidar is about 30 degrees, the angle between the laser beams 222 and thehorizontal plane ranges from −20 degrees to +10 degrees, and the anglesbetween every two adjacent laser beams 222 are approximately equal.Applying these numbers to FIG. 11B, the vertical angle resolution of theLidar is about 0.9375 degrees (30 degrees/32). Applying these numbers toFIG. 11C, after the rotation, the vertical angle resolution of the Lidaris about 0.0293 degrees (30 degrees/(32×32), which corresponds to ahigher angular resolution. In some other embodiments, the opticalsplitting apparatus 123 can also comprise a 5 by 5 beam splitter, 8 by 8beam splitting, 16 by 16 beam splitting, or 5 by 8 beam splitting.

FIG. 11D is a graphical diagram of light spots formed on a plane bylaser beams 222 of a Lidar, consistent with various embodiments of thepresent disclosure. In some embodiments, instead of the two-dimensionalDammann grating described above, the optical splitting apparatus 123 maycomprise a one-dimensional grating (e.g., a one-dimensional Dammanngrating) with a grating period d. The angle between the propagationdirection of the laser beams 222 and the y direction is:

$\theta_{y} = {{\arcsin \left( \frac{k_{y}}{k} \right)} = {\arcsin \left( {n_{y}\frac{\lambda}{d_{1}}\cos \mspace{14mu} \phi} \right)}}$

where λ is the wavelength of the laser beam, and φ is the acute anglebetween the direction d1 and the y direction of the optical splittingapparatus 123. N_(y) is the diffraction order in the y direction.

As shown in FIG. 11D, light spots 341 are obtained when the includedangle between the d direction and the y direction is 0 (the d (341)direction shown in the figure corresponds to this configuration), andlight spots 342 are obtained when the included angle between the ddirection and the y direction is φ (the d (342) direction shown in thefigure corresponds to this configuration).

With the rotation of the optical splitting apparatus 123, the distancebetween adjacent light spots decreases in the y direction, the anglebetween each two adjacent laser beams 222 decreases, and the angularresolution of the Lidar in the vertical direction increases.

As shown in FIG. 11D, the vertical range covered by the beams 341 is r1,and the vertical range covered by the beams 342 is r2, and r1 is largerthan r2. Thus, the rotation may cause a decrease in the vertical fieldof view for the one-dimensional grating.

As such, the optical splitting apparatus 123 is an m by 1one-dimensional grating with a grating period d, and the wavelength ofthe first laser beam is λ, m is the number of split beams. The angle ofrotation of the optical splitting apparatus 123 may be smaller than:

$\arccos\left( \frac{d\mspace{14mu} \sin \frac{\alpha}{m}}{\lambda} \right)$

α is a preset field of view (e.g., 5 degrees), such that the real fieldof view is larger than the preset field angle alpha.

The optical splitting apparatus 123 can be fixed or can rotate aroundthe optical axis 89 or another line parallel to the optical axis 89 byany configurable degree. When the position of the optical splittingapparatus 123 is fixed, the d direction and the y direction of theoptical splitting apparatus 123 can set to a certain angle, so that theangle of the adjacent second laser beams in the y direction is reducedto improve the angular resolution in the y direction.

As such, the emitting apparatus 120 can be provided with a rotationshaft which intersects with the reverse direction of the laser beam 111transmission direction. The emitting apparatus 120 can rotate around therotation shaft. The optical splitting apparatus 123 can split the laserbeam in a light splitting direction perpendicular to the optical axis,and the plane where the light splitting direction and the optical axisare located is a light splitting plane. The angle between the lightsplitting direction and the rotation shaft is larger than or equal to 0degree, and is smaller than 90 degrees. The optical splitting apparatus123 may comprise a grating. The optical splitting apparatus 123 can beprovided with a first grating period in the first direction, and thelight splitting direction is the first direction.

FIGS. 11E-11G are light path diagrams of a Lidar, consistent withvarious embodiments of the present disclosure. FIG. 11F is an enlargedlight path diagram of portion 41 shown in FIG. 11E. FIG. 11G is anenlarged light path diagram of the echo light beam shown in FIG. 11E. Insome embodiments, the Lidar system further comprises a galvanometer,wherein: the galvanometer is configured to rotate about a vibrationrotating shaft; the galvanometer comprises a first reflecting surfaceconfigured to reflect the third light beams out of the Lidar during therotation of the galvanometer; and an angle between the vibrationrotating shaft and a normal line of the first reflecting surface islarger than zero. The Lidar system may further comprise asemi-transparent mirror and a receiving device, wherein: at least aportion of the third light beams passes through the optical splittingapparatus and the semi-transparent mirror to reach a first reflectingsurface of the galvanometer; at least a portion of the third light beamsreflected by the first reflecting surface is reflected back to the firstreflecting surface as echo beams; and the semi-transparent mirrorcomprises a second reflecting surface configured to reflect the echolight beams reflected by the first reflecting surface into the receivingdevice. The Lidar system may further comprise a receiving converginglens, wherein: the receiving converging lens is configured to convergethe echo light beams reflected by the semi-transparent mirror into thereceiving device; and a distance between the receiving device and afocal point of the receiving converging lens is smaller than half of afocal depth of the receiving converging lens.

As shown in FIGS. 11E-11G, the Lidar may further comprise a laser 410corresponding to the laser 121 and an optical splitting apparatus 420corresponding to the optical splitting apparatus 123. The Lidar mayfurther comprise a collimating lens 451, a focusing lense 452, asemi-transparent mirror 453, a galvanometer 450 (e.g., laser scanninggalvanometer, micro-electro-mechanical scanning galvanometer), areceiving converging lens 454, and a receiving device 430. Thegalvanometer 450 comprises a first reflecting surface 450 a configuredto reflect laser beams. The galvanometer 450 may be provided with avibration rotating shaft (not shown), and configured to rotate aroundthe vibration rotating shaft. The angle between the vibration rotatingshaft and the normal line of the first reflecting surface 450 a islarger than zero. FIG. 11F shows the light path until reaching thegalvanometer 450, and FIG. 11G shows the light path as the laser beamreflects back from the object 409.

The rotation of the vibration rotating shaft may be driven by thegalvanometer 450, such that the propagation direction of the laser beamreflected by the first reflecting surface 450 a can be changed, therebyincreasing the scanning range and the field of view of the Lidar. Therotation of the galvanometer 450 only needs to cover the angle betweenthe adjacent laser beams reflecting off the galvanometer 450 to maximizethe field of view of the Lidar. Thus, the combination of thegalvanometer 450 and the optical splitting apparatus 420 can obtain alarge field of view angle through a small angular rotation of thegalvanometer 450, thereby reducing the rotation range and frequency ofthe galvanometer 450 and improving the scanning frame frequency of theLidar.

In some embodiments, the optical splitting apparatus 420 comprises aone-dimensional grating (e.g., one-dimensional Dammann grating). Throughthe beam splitting device 420, a plurality of laser beams in the sameplane (referred to as a propagation plane) can be obtained from thelaser beam emitted by the laser 410. The first reflecting surface 450 aand the propagation plane have an intersecting line, the angle betweenthe vibration rotating shaft and the intersecting line is larger than 0degrees, and the angle between the vibration rotating shaft and theintersecting line is 90 degrees.

In some embodiments, the laser 410 is provided with a scanning rotatingshaft (not shown in the figure and similar to the rotation shaftdescribed above) which intersected with the propagation direction of theemitted laser beam. The angle between the vibration rotating shaft andthe scanning rotating shaft is larger than 0 degrees, the angle betweenthe vibration rotating shaft and the scanning rotating shaft is 90degrees.

In some embodiments, the vibration rotating shaft is parallel to thefirst reflecting surface 450 a, which is beneficial to the installationof the galvanometer 450. In some embodiments, the vibration rotatingshaft may have an acute angle between the vibration rotating shaft andthe first reflecting surface 450 a.

As shown in FIG. 11E and FIG. 11F, the Lidar may further comprise thecollimating lens 451 and the focusing lens 452. The collimating lens 451is configured to collimate a plurality of laser beams, so that thepropagation directions of the plurality of laser beams are brought toparallel to each other. The focusing lens 452 is configured to convergethe collimated laser beams to the first reflecting surface 450 a of thegalvanometer 450. The distance between the optical splitting apparatus420 and the focal point of the collimating lens 451 is less than half ofthe focal depth of the collimating lens 451. For example, the opticalsplitting apparatus 420 is located at the focal plane of the collimatinglens 451. The distance between the galvanometer 450 and the focusinglens 452 is smaller than half of the focal depth of the focusing lens452. For example, the galvanometer 450 is located at the focal plane ofthe focusing lens 452.

The focal point of the focusing lens 452 may coincide with the focalpoint of the collimating lens 451, and the optical axis of the focusinglens 452 may coincide with the optical axis of the collimating lens 451.The configuration of the collimating lens 451 and the focusing lens 452can increase the number of second laser beams converged to the firstreflecting surface 450 a of the galvanometer 450, thereby increasing thenumber of laser beams reflected by the galvanometer 450 and the field ofview of the Lidar.

In some embodiments, the laser beam emitted by the laser 410 is linearlypolarized. Since the polarization of the linearly polarized light isdirectional, the depolarization of the Lidar is small. Based on thepolarization direction of the emitted laser beam, stray light withdifferent polarization directions can be filtered out, thereby improvingthe signal-to-noise ratio of the Lidar.

In addition, as shown in FIG. 11E and FIG. 11G, the Lidar furthercomprises a semi-transparent mirror 453 configured to enable at leastpart of the incident laser beams to penetrate through and impinge ontothe first reflecting surface 450 a of the galvanometer 450. Thesemi-transparent mirror 453 comprises a second reflecting surface 453 aconfigured to reflect the echo light beam reflected by the galvanometer450 into the receiving device 430.

The semi-transparent mirror 453 can separate the echo light beam (laserbeams reflected back from an object 409) from the focused laser beam(laser beams focused by the focusing lens 452), so that the interferenceof the focused laser beam to the receiving device 430 can be prevented,and the precision of the Lidar can be improved. The semi-transparentmirror 453 can also be used for realizing optical path overlapping, sothat the optical path of the Lidar is shortened, and the size of theLidar can be effectively reduced. As shown in FIG. 11E, the secondreflecting surface 453 a of the semi-transparent mirror 453 may face thefirst reflecting surface 450 a of the galvanometer 450.

In some embodiments, the Lidar further comprises the receivingconverging lens 454 configured to converge echo light beam reflected bythe semi-transparent mirror 453 into the receiving device 430. Thedistance between the receiving device 430 and the focal point of thereceiving converging lens 454 is smaller than half of the focal depth ofthe receiving converging lens 454.

The distance between the receiving converging lens 454 and the receivingdevice 430 (e.g., detector) is smaller than half of the focal depth ofthe receiving converging lens 454. For example, the detector is locatedat the focal plane of the receiving converging lens 454.

The Lidar can obtain a large field of view through a small rotation ofthe galvanometer 450. In some embodiments, the optical splittingapparatus 420 comprises a 1 by 9 beam splitting one-dimensional Dammanngrating. The focusing lens 452 converges laser beams to a centerposition of the first reflecting surface 450 a. The plane where anypoint on the surface of the object 409 is located can be a target plane.As shown, the distance between the target plane and the center positionof the first reflecting surface 450 a is 1, and the distance between thetarget plane and the center position of the first reflecting surface 450a is L (which will be referred to in discussions of FIGS. 11H-11Jbelow).

FIGS. 11H-11J are graphical diagrams of light spots formed by the laserbeams on the target plane at different times of the galvanometervibration, consistent with various embodiments of the presentdisclosure. An x-y-z coordinate system is provided established on thetarget plane. The x direction and the y direction are provided in thefigures, and the z direction is perpendicular to the x-y plane. The ydirection is parallel to the grating period direction of the opticalsplitting apparatus 420, that is, the y direction is parallel to thelight splitting direction of the optical splitting apparatus 420.

As shown in FIG. 11H, in some embodiments, the plurality of laser beamssplit by the optical splitting apparatus 420, reflected by the firstreflecting surface 450 a, and projected to the object 409's target planecan form a plurality of light spots 441. The light spots 441 form a 1×9light spot array on the target plane. The light spot array has an arrayperiod dy in the y direction, namely, the distance between the adjacentlight spots 441 in the y direction is dy. For discussion, it can beassumed that when the first reflecting surface 450 a rotates in aclockwise direction around the vibration rotating shaft, the rotatingangle of the galvanometer 450 is a positive value, and when the firstreflecting surface 450 a rotates in a counter-clockwise direction aroundthe vibration rotating shaft, the rotating angle of the galvanometer 450is a negative value.

If the incident angle of the laser beam impinging on the galvanometer450 does not change, when the galvanometer 450 rotates by 0, the normalrotation angle of the first reflecting surface 450 a is also θ, andaccording to the optical reflection principle, the rotation angle of thelaser beam reflected by the first reflecting surface 450 a is 20.

As shown in FIG. 11I, when the rotation angle of the galvanometer 450 isθ=dy/4L, and the rotation angle of the laser beam reflected by the firstreflecting surface 450 a is 2θ=dy/2L. The rotated laser beams form lightspots 442 on the target plane, and the light spots 442 are shifted inthe y-positive direction from the locations of the light spots 441. Thegap between the respective neighboring pair of light spot 442 and lightspot 441 is about dy/2.

As shown in FIG. 11J, when the rotation angle of the galvanometer 450 isθ=−dy/4L, the rotation angle of the laser beam reflected by the firstreflecting surface 450 a is 20=−dy/2L, the rotated laser beams formlight spots 443 on the target plane. The light spots 443 are shifted inthe y-negative direction from the locations of the light spots 441, andthe gap between the respective neighboring pair of light spot 443 andlight spot 441 is about dy/2.

As shown FIGS. 11I and 11J, when the rotation angle of the galvanometer450 is between −dy/4L and dy/4L, the gap between laser beams before therotation can be scanned by the laser beams with the rotation, so thatthe field of view of the Lidar is the range covered by the reflectedbeams with the rotation of the galvanometer 450.

In some embodiments, the optical splitting apparatus 420 comprises aone-dimensional Dammann grating with 1×9 beam splitting. In the ydirection, the field of view angle of the Lidar is 9dy/L. If dy/L is 10degrees, the maximum angle of rotation of the galvanometer 450 is 5degrees, and the visual field angle of the Lidar in the y direction is90 degrees. Thus, the combination of the galvanometer and the opticalsplitting apparatus 420 can obtain a large field of view angle through asmall galvanometer rotation, thereby reducing the rotation range andfrequency of the galvanometer 450 and improving the scanning framefrequency of the Lidar.

In some embodiments, when the vibration rotating shaft is parallel tothe propagation plane and parallel to the first reflecting surface 450a, the galvanometer 450 can rotate around the vibration rotating shaftto increase the field angle of the Lidar in the direction perpendicularto the scanning rotating shaft. When the vibration rotating shaft andthe propagation plane are at an acute angle, the galvanometer 450 canrotate around the vibration rotating shaft to increase the field of viewof the Lidar in the direction perpendicular to the scanning rotatingshaft and in the direction parallel to the scanning rotating shaft.

In some embodiments, the optical splitting apparatus 420 comprises atwo-dimensional Dammann grating. When the vibration rotating shaft isnot perpendicular to the first reflecting surface 450 a, the vibratingmirror may rotate around the vibration rotating shaft, and the vibratingmirror can rotate through a smaller galvanometer rotating angle, so thatthe Lidar has a large field of view angle perpendicular to the directionof the scanning rotating shaft and parallel to the direction of thescanning rotating shaft, the scanning range of the laser beams can beeffectively expanded, and the angle resolution and the field of viewangle of the Lidar in all directions can be increased.

FIG. 12 is a schematic structural diagram of an emitting apparatus 500of a Lidar, consistent with various embodiments of the presentdisclosure. The emitting apparatus 500 may be used in place of theemitting apparatus 120 in FIG. 2. That is, the emitting apparatus 120may alternatively be the emitting apparatus 500 within the scope of thisdisclosure. For example, the emitting apparatus 500 may be used in placeof the emitting apparatus 120 to be incorporated into the Lidar 200.

In some embodiments, a Lidar system may comprise an emitting apparatus(e.g., emitting apparatus 500) and a receiving apparatus (e.g.,receiving apparatus 130). The emitting apparatus may comprise a firstlaser (e.g., laser 121 a), a second laser (e.g., laser 121 b), and anoptical splitting apparatus (e.g., optical splitting apparatus 211). Thefirst laser is configured to emit a first laser beam (e.g., laser beam117 a), and the second laser is configured to emit a second laser beam(e.g., laser beam 117 b). As shown, in one example, the lasers 121 a and121 b can be vertically stacked and emit beams in a horizontaldirection. The emitted laser beams before reaching the first converginglens 210 and being converged are emitted in an emission direction atdifferent vertical heights and are parallel. The vertical direction canbe referred to a distribution direction normal to the emissiondirection, and the lasers may be distributed non-uniformly along thedistribution direction when the number of lasers increases. Variousother modifications to the laser positions can also be included (e.g.,by adding optical or mechanical light path manipulation) as long as thelasers are distributed non-uniformly in the direction that correspondsthe Lidar line scan (before the Lidar rotates) and contribute the anon-uniform laser beam spot distribution along the Lidar's line scan.For example, a denser laser distribution towards the middle of thedistribution direction contributes to a denser laser beam spotdistribution towards the middle of the line scan.

In some embodiments, the optical splitting apparatus is configured tosplit the first laser beam into a plurality of third laser beams (e.g.,laser beam 227 a) with different propagation directions, and split thesecond laser beam into a plurality of fourth laser beams (e.g., laserbeam 227 b) with different propagation directions. The third laser beamsat least partially overlap with the fourth laser beams at an overlappingregion. The receiving apparatus is configured to receive echo beamsreflected from at least one of the third laser beams or the fourth laserbeams by a target.

In some embodiments, the emitting apparatus 500 comprises a plurality oflasers (e.g., two lasers 121 a and 121 b are shown in the figure), aplurality of optional beam expanding and collimating apparatuses 122 aand 122 b, a first converging lens 210, and an optical splittingapparatus 211 (e.g., the one-dimensional Dammann grating describedabove, the two-dimensional Dammann grating described above, etc.). Theoptical splitting apparatus 211 may be similar to the optical splittingapparatus 123 and to the optical splitting apparatus 420 describedabove. The plurality of lasers may simultaneously emit a plurality oflaser beams 117. For example, the laser 121 a may emit a first laserbeam 117 a, and the laser 121 b may emit a second laser beam 117 b. Thelaser beams 117 may be split by the optical splitting apparatus 211 toobtain laser beams 227. For example, the first laser beam 117 a is splitby the optical splitting apparatus 211 to obtain third laser beams 227a, and the second laser beam 117 b is split by the optical splittingapparatus 211 to obtain fourth laser beams 227 b. Due to the beamsplitting, the number of laser beams 227 is larger than the number oflaser beams 117, thereby increasing the field of view and the angularresolution of the Lidar.

In some embodiments, the propagation directions of the laser beams 117emitted by the plurality of lasers are the same (that is, the laserbeams 117 before entering the first converging lens 210 propagate in thesame direction). In some embodiments, the propagation directions of thelaser beams emitted by the plurality of lasers may be different.

In some embodiments, the plurality of beam expanding and collimatingapparatuses respectively correspond to the plurality of lasers. Asshown, the laser beam emitted by the laser 121 a passes through the beamexpanding and collimating apparatus 122 a, and the laser beam emitted bythe laser 121 b passes through the beam expanding and collimatingapparatus 122 b. The plurality of beam expanding and collimatingapparatuses 122 a and 122 b are respectively configured to increase thespot diameters and reduce the divergence angles of the laser beams 117that have travelled the same distance from the plurality of lasers. Thatis, a first beam expanding and collimating apparatus is configured toincrease a spot diameter of the first laser beam and reduce a divergenceangle of the first laser beam, and a second beam expanding andcollimating apparatus is configured to increase a spot diameter of thesecond laser beam and reduce a divergence angle of the second laserbeam.

In some embodiments, the first converging lens 210 is configured toconverge the laser beams 117 emitted by the plurality of lasers to theoptical splitting apparatus 211. The first converging lens 210 canchange propagation directions of the laser beams 117, for example, frombeing in parallel to converging. Since the propagation directions of thelaser beams 117 reaching the optical splitting apparatus 211 aredifferent, the propagation directions of the laser beams 227 obtainedfrom the laser beams 117 are different, thereby further increasing theangular resolution of the Lidar.

In some embodiments, a distance from the optical splitting apparatus 211to the focal plane of the first converging lens 210 is less than half ofthe focal depth of the first converging lens 210. For example, theoptical splitting apparatus 211 is located on the focal plane of thefirst converging lens 210.

In some embodiments, as shown in FIG. 12, the combination of the lasers121 a and 121 b (or a similar combination with more lasers) can producea non-uniform angular distribution of laser beams. Unlike the lasers 10in the conventional Lidar described above, in which the laser beams 29have a uniform angular distribution, here in the emitting apparatus 500,the laser beams 117 from two or more lasers are incidentnon-perpendicularly to the optical splitting apparatus 211 to producebeams 227 of a non-uniform angular distribution. Base on the incidentangles of the laser beams 117, the solid-line laser beams 227 a maypartially overlap with the dash-line laser beams 227 b to achieve theoverall non-uniform angular distribution for the laser beams 227. Thenon-uniform angular distribution can correspond to a non-uniform planardistribution of beams. For example, at position 180 (represented by adot-dash line), the laser beams 227 are denser in a region near theoptical axis of the converging lens 210 where the overlap occurs, andare sparser in regions away from the optical axis in both up and downdirections. Further, the non-uniform spread of the laser beams 227 canbe tunable by adjusting appropriate optical and/or mechanicalcomponents.

Such non-uniform spread of laser beams 227 can lead to a greater angularresolution, for example, in a configurable range of directions and allowmore accurate detection of targets in the corresponding region (e.g.,central region) among the entire spread of the laser beams 227, whilestill attaining a large field of view jointly covered by all laserbeams. This result of non-uniform distribution of beams is desirable forvarious applications such as vehicle-mounted Lidar, where enhanced andmore accurate target detections are needed at a horizontal level (e.g.,detecting pedestrians for predicting their next moves, detecting precise3D information of vehicles for determining the vehicle types), while thesurrounding environments of the targets only require standard leveldetections. For example, if the lasers are mounted vertically in aLidar, in the vertical direction, the emitted beams may be dense in themiddle part and sparse in the upper and lower parts among a verticalbeam spread. As the Lidar rotates, the vertical spread of non-uniformlydistributed beams can scan a vertical area ahead, where the middle stripof the vertical area has denser beams for detection and thus increaseddetection accuracy. Since external objects like pedestrians, othervehicles, and obstacles are usually at the same horizontal level as thevehicle, the external objects will be more likely to be detected bybeams in the middle strip, and therefore can afford more accuratedetection.

In some embodiments, a target reflects a portion of the laser beams 227to form the echo beams, which can be captured by the receiving apparatus130 for detecting the target (e.g., determining its direction). Forexample, the target may fall in the overlapping region and reflect aportion of the third laser beams and a portion of the fourth laser beamssimultaneously in the overlapping region to form the echo beams. In someembodiments, a first detector is configured to receive echo beams thatare reflected off the target from the third laser beams (e.g., a portionof the third laser beams) for detecting the target, and a seconddetector is configured to receive echo beams that are reflected off thetarget from the fourth laser beams (e.g., a portion of the fourth laserbeams) for detecting the target. Thus, the target affords more accuratedetection.

In some embodiments, when implementing the emitting apparatus 500 in theLidar 200 in place of the emitting apparatus 120, the optical axis ofthe first converging lens 210 is perpendicular to the rotating shaft141. The plurality of lasers (e.g., 121 a, 121 b) are arranged in adirection along (parallel to) the rotating shaft 141, and thepropagation directions of the laser beams emitted by the plurality oflasers are in parallel to the optical axis of the first converging lens210. The first converging lens 210 can cause the laser beams 117 toemerge from the first converging lens 210 at different angles withrespect to the rotation shaft 141, so that the angles between thepropagation directions of the laser beams 227 and the rotation shaft 141are different, and the resolution and the field of view of the Lidar areincreased in the direction along the rotating shaft 141.

In some embodiments, the Lidar is mounted on a vehicle configured tomove on a surface and is rotatable with respect to a vertical axisrelative to the surface. The first and second lasers are disposed in avertical plane relative to the surface and configured to emit the firstand second laser beams respectively in a direction along the surface.When the Lidar is not rotating with respect to the vertical axis, thefirst, second, third, and fourth laser beams propagate in the verticalplane, causing the third and fourth laser beams to scan a distantvertical line. When the Lidar is rotating with respect to the verticalaxis, the vertical plane rotates with respect to the vertical axis,causing the third and fourth laser beams to scan a distant verticalsurface. The emitting apparatus of the Lidar may comprise a rotatingshaft, and the Lidar may rotate about the rotating shaft, the rotatingshaft acting as the vertical axis. The third and fourth laser beamsdiverge from the Lidar. The first, second, third, and fourth laser beamsand the rotating shaft are in the vertical plane.

FIG. 13 is a schematic structural diagram of an emitting apparatus 501of a Lidar, consistent with various embodiments of the presentdisclosure. The emitting apparatus 501 is similar to the emittingapparatus 500 described above, except that three instead of two lasersare shown here. The emitting apparatus 501 may comprise three lasers 511similar to the lasers 121 a and 121 b, collimating apparatuses 514similar to the collimating apparatuses 122, converging lens 512 similarto the first converging lens 210, and an optical splitting apparatus 520similar to the optical splitting apparatus 211. The laser beams 510 amay be split into laser beams 520 b, which are similarly non-uniform inthe vertical direction.

In some embodiments, the optical splitting apparatus 520 comprises atwo-dimensional grating (e.g., two-dimensional Dammann grating). Theoptical splitting apparatus 520 may be configured to rotate about ashaft parallel to (e.g., aligned with) the optical axis of theconverging lens 512. FIG. 14 is a graphical diagram illustrating lightspots on a target plane before and after the optical splitting apparatus520 rotates around the shaft, consistent with various embodiments of thepresent disclosure. The rotation may be similar to the rotationdescription above. As shown, the rotation causes denser beam spots inthe target plane, thereby increasing the angle resolution of the Lidar.The field of view of the Lidar can also be effectively expanded as thedimension of the area range covered by the beam spots increases.

In some embodiments, the emitting apparatus 501 may be modified into anemitting apparatus 601 shown in FIG. 15. FIG. 15 is a schematicstructural diagram of an emitting apparatus 501 of a Lidar, consistentwith various embodiments of the present disclosure. The emittingapparatus 501 and the emitting apparatus 601 are similar except thatlasers 611 of the emitting apparatus 601 may emit non-parallel laserbeams pointing towards an optical splitting apparatus 620 (similar tothe various optical splitting apparatuses described above) of theemitting apparatus 601. That is, at least two of the light emittingdirections of the plurality of lasers beams 610 a are non-parallel. Insome embodiments, the laser beams 610 a propagate in differentdirections, for example, each two of the laser beams 610 a may intersect(e.g., at the light splitting apparatus 620). Thus, the opticalcomponents such as converging lenses and certain collimating apparatusescan be obviated, and the optical path of the Lidar is simplified. Inthis case, the horizontal direction may be referred to as an emissiondirection, and the vertical direction may be referred to as adistribution direction. When the number of lasers increases, the lasersmay be distributed non-uniformly along the distribution direction.

FIG. 16 is a block diagram of a detection method 600, consistent withvarious embodiments of the present disclosure. Corresponding to thedescription of FIG. 9 and FIG. 10 above, the method 600 comprises: atstep 602, emitting (e.g., from the emitting apparatus 120, 500, 501, or601) a laser beam towards a target, the laser beam split by an opticalsplitting apparatus (e.g., the optical splitting apparatus 123) into aplurality of laser beams with different propagation directions, whereinat least some of the split laser beams are reflected by the target asecho beams, at step 604, receiving (e.g., by the receiving apparatus130) the echo beams; and step 606, determining a distance of the target(e.g., a distance from the target to the Lidar system) based on the echobeams. In some embodiments, the laser beams may be respectively emittedby a plurality of lasers. The lasers may be non-uniformly distributed asdescribed herein. The quantity of the detectors 131 in the receivingapparatus 130 is the same as or different from the quantity of thelasers or the laser beams 222.

Alternatively, corresponding to the description of FIG. 12 and FIG. 10above, the detection method comprises: emitting (e.g., from the emittingapparatus 500) a first laser beam and a second laser beam towards atarget, the first laser beam split by an optical splitting apparatus(e.g., the optical splitting apparatus 123) into a plurality of thirdlaser beams with different propagation directions, the second laser beamsplit by an optical splitting apparatus (e.g., the optical splittingapparatus 123) into a plurality of fourth laser beams with differentpropagation directions, wherein at least some of the third and fourthlaser beams are reflected by the target as echo beams, at step 604,receiving (e.g., by the receiving apparatus 130) the echo beams; andstep 606, detecting the target based on the echo beams. In someembodiments, the quantity of the detectors 131 in the receivingapparatus 130 is the same as the quantity of the laser beams 227 a and227 b. In some embodiments, the quantity of the detectors is differentfrom the quantity of the laser beams.

As described, an exemplary Lidar may include an optical splittingapparatus, which can split each laser beam into the plurality of laserbeams propagating along different directions. The laser beamspropagating along different directions can detect targets located indifferent directions, so as to increase the field of view and theangular resolution of the Lidar. Moreover, the optical splittingapparatus splits the laser beam into the plurality of laser beams, whichcan be obtained by using one laser or a small number of lasers, so as togreatly reduce the quantity of lasers, thereby reducing the costs andthe packaging difficulty of the Lidar. Thus, the disclosed Lidar canhave a relatively large field of view and a relatively high angularresolution at a low cost.

Further, the optical splitting apparatus may comprise a Dammann grating.The Dammann grating can split the laser beam into a plurality of laserbeams of similar intensities, so that no excessively low intensity beammay affect detection, thereby improving the performance of the Lidar.

Further, the angles between the propagation directions of the pluralityof split laser beams and the rotating shaft are different, so that theresolution and the field of view of the Lidar that are along a directionparallel to the rotating shaft can be increased, so that the Lidar willhave a relatively high resolution and field of view in both a directionperpendicular and a direction parallel to the rotating shaft. When therotating shaft is perpendicular to the horizontal plane, the verticalangular resolution and the vertical field of view of the Lidar can beincreased.

Further, the first converging lens can make angles between the laserbeams emergent through the first converging lens and the horizontalplane different, so that the angles between the propagation directionsof the split laser beams and the rotation shaft are different, therebyincreasing the resolution and the field of view of the Lidar along thedirection parallel to the rotating shaft. When the rotating shaft isperpendicular to the horizontal plane, the vertical angular resolutionand the vertical field of view of the Lidar can be increased.

Further, the emitting apparatus may comprise a plurality of lasers. Theplurality of lasers may simultaneously emit a plurality of laser beams,and then more laser beams can be obtained after the emitted laser beamsare split by the optical splitting apparatus, thereby increasing thefield of view and the angular resolution of the Lidar. Moreover, whenthe split laser beams from different lasers overlap, the overlappingregion has a higher beam concentration, from which targets can bedetected more accurately. When the lasers are arranged vertically in aLidar, a non-uniform distribution of laser beams with a high density atthe horizontal level of the Lidar can be achieved. Thus, targets at thehorizontal level with respect to a vehicle-mounted Lidar can be moreaccurately detected.

The embodiments illustrated herein are described in sufficient detail toenable those skilled in the art to practice the teachings disclosed.Other embodiments may be used and derived therefrom, such thatstructural and logical substitutions and changes may be made withoutdeparting from the scope of this disclosure. The detailed description,therefore, is not to be taken in a limiting sense, and the scope ofvarious embodiments is defined only by the appended claims, along withthe full range of equivalents to which such claims are entitled.

In this disclosure, some conventional aspects have been simplified oromitted. A person skilled in the art should understand that variationsor alternatives derived from these implementations will fall within thescope of the present disclosure. A person skilled in the art shouldunderstand that the disclosed components or features can be combined invarious manners to form a plurality of variations. In some embodiments,the converging lens 210 and optical splitting apparatus 211 of FIG. 12can be applied to various parallel laser beam paths shown in FIG. 4A toFIG. 6. The converging lens 210 and optical splitting apparatus 211 canreceive and split two or more laser beams simultaneously. For example,the converging lens 210 and optical splitting apparatus 211 can beapplied to any dense laser beam region (e.g., between 3° and −7° in FIG.6) to obtain more split beams to further densify beams towards a middlepart of the region in the vertical direction. For another example, theconverging lens 210 and optical splitting apparatus 211 can receive allthe beams in any of the FIG. 4A to FIG. 6 to obtain more split beams andfurther densify beams towards a middle part of the correspondingstructure in the vertical direction. Similarly, the laser(s) 121, 410,511, and 611 can each comprise one laser or two or more lasers. For twoor more lasers, such laser combination can comprise any of the laserstructures 290, 299, 390, 490, and 690 described with reference to FIG.3 to FIG. 8, or a similar version (e.g., with more or fewer lasers) aslong as the lasers are non-uniformly distributed in the verticaldirection. Referring to FIGS. 4A-15, in some embodiments, a Lidar systemmay comprise: an emitting apparatus comprising a plurality of lasersconfigured to emit laser beams (e.g., parallel laser beams as shown inFIGS. 4A-6, 9, 12, and 13) respectively in an emission direction; anoptical splitting apparatus configured to receive and split the laserbeams into a plurality of split laser beams with different propagationdirections, and a receiving apparatus configured to receive echo beamsto detect a target, wherein the echo beams are a portion of the splitbeams reflected by the target. The lasers are non-uniformly disposed ina distribution direction normal to the emission direction, aconcentration of the lasers first increases and then decreases along thedistribution direction (e.g., denser in the middle), and at least someof the split laser beams overlap. The receiving apparatus may comprisesa plurality of detectors configured to receive the echo beams. Each ofthe detectors corresponds to one of the lasers and is configured toreceive light originated from the corresponding laser. Various othermodifications to the laser positions can also be included (e.g., byadding optical or mechanical light path manipulation) as long as thelasers are distributed non-uniformly in the direction that correspondsthe Lidar line scan (before the Lidar rotates) and contribute the anon-uniform laser beam spot distribution along the Lidar's line scan.For example, a denser laser distribution towards the middle of thedistribution direction contributes to a denser laser beam spotdistribution towards the middle of the line scan.

As discussed with reference to FIGS. 4A-8, the lasers may be disposed onone or more vertically disposed supporting bodies. The distributiondirection may be in the vertical direction. The emission direction maybe normal to the vertical direction.

In some embodiments, the Lidar is mounted on a vehicle configured tomove on a surface and is rotatable with respect to a vertical axisrelative to the surface. The emitted laser beams are parallel to eachother and propagate in the emission direction. The distributiondirection is normal to the surface. The emission direction is parallelto the surface. When the Lidar is not rotating with respect to thevertical axis, the split laser beams propagate in a vertical plane andthe Lidar scans a distant vertical line of laser beam spotscorresponding to the split laser beams, and the concentration of thelaser beam spots first increases and then decreases along the distantvertical line. When the Lidar rotates with respect to the vertical axis,the Lidar causes the distant vertical line scan to turn into a distantvertical surface scan.

As discussed with reference to FIGS. 11E-11G, in some embodiments, theemitting apparatus further comprises a semi-transparent mirror and agalvanometer. Past through the optical splitting apparatus and beforereaching the target, the split laser beams passes the semi-transparentmirror to reach the galvanometer. The galvanometer is configured torotate and reflect the split laser beams out of the Lidar during therotation of the galvanometer. The galvanometer is configured to reflectthe portion of the split beams reflected by the target to thesemi-transparent mirror. The semi-transparent mirror is configured toreflect the portion of the split beams to the receiving apparatus.

Combining the non-uniform distribution of lasers with the opticalsplitting structure can reduce the number of lasers required to achievethe same angular resolution and/or field of view of the Lidar, therebylowering the Lidar cost and simplifying its structure. If keeping thesame number of lasers, the angular resolution and/or field of view ofthe Lidar can be further improved from having the non-uniform laserdistribution or the optical splitter alone. Therefore, as shown, one wayto obtain a non-uniform angular distribution of laser beams is to spliteach of two or more laser beams to obtain an overlapping region withdenser beams. Another way is to obtain a physical structure with avarying density of lasers along a (e.g., vertical) direction. The abovetwo implementations can also be combined to further densify beams in aconfigurable region, which can be particularly desirable in applicationssuch as vehicle-mounted Lidar.

What is claimed is:
 1. A Lidar system comprising a rotor, wherein therotor comprises: a supporting body that has a longitudinal axis in avertical direction of the Lidar system; and a plurality of lasersdisposed on the supporting body and configured to emit laser beamsrespectively, wherein the lasers are distributed non-uniformly along thevertical direction from a highest to a lowest of the lasers.
 2. TheLidar system of claim 1, wherein: the lasers include a first group oflasers disposed along the vertical direction at equal intervals and asecond group of lasers disposed along the vertical direction at equalintervals; and the second group of lasers is disposed at positionscorresponding to the intervals of the first group of lasers.
 3. TheLidar system of claim 2, wherein a number of the second group of lasersis less than a number of the first group of lasers.
 4. The Lidar systemof claim 2, wherein the second group of lasers is disposed in a verticalplane parallel with another vertical plane in which the first group oflasers is disposed, and the second group of lasers is disposed at alocation close to a middle portion of the first group of lasers.
 5. TheLidar system of claim 2, wherein the second group of lasers is disposedat positions corresponding to middle points of the intervals of thefirst group of lasers.
 6. The Lidar system of claim 1, wherein: adensity of the lasers on the supporting body first increases and thendecreases along the vertical direction from a highest light laser to alowest laser of the lasers.
 7. The Lidar system of claim 1, wherein: thelasers distributed non-uniformly along the vertical direction comprisesa sparser concentration of the lasers at each of two ends of a verticalfield of view of the Lidar system and a denser concentration of thelasers towards a center of the vertical field of view of the Lidarsystem.
 8. The Lidar system of claim 1, further comprising a scanningdevice, wherein: the scanning device is configured to rotate about avibration rotating shaft; the scanning device comprises a firstreflecting surface configured to reflect light out of the Lidar systemduring the rotation of the scanning device; and an angle between thevibration rotating shaft and a normal line of the first reflectingsurface is larger than zero.
 9. The Lidar system of claim 1, furthercomprising one or more first reflectors and an optical emitting device,wherein the laser beams are reflected by one or more first reflectorsand pass through the optical emitting device to illuminate on anexternal object.
 10. The Lidar system of claim 9, wherein the opticalemitting device comprises a collimation lens or a collimation lensassembly.
 11. The Lidar system of claim 9, further comprising a lightfiltering device disposed outside an inner cavity of the rotor.
 12. TheLidar system of claim 11, further comprising a light receiving device,wherein the light filtering device is configured to filter out ambientlight for the light receiving device.
 13. The Lidar system of claim 12,wherein the light filtering device is disposed on a light path ofreflected light off the external object and located upstream of thelight receiving device.
 14. The Lidar system of claim 12, wherein thelight receiving device comprises a focusing lens or a focusing lensassembly.
 15. The Lidar system of claim 13, further comprising one ormore second reflectors and a light detecting device, wherein the one ormore second reflectors is disposed on the light path of the reflectedlight downstream of the light receiving device and configured to reflectthe reflected light to the light detecting device.
 16. A Lidar system,comprising: an emitting apparatus comprising: a supporting body that hasa longitudinal axis in a vertical direction of the Lidar system; and aplurality of lasers disposed on the supporting body and configured toemit laser beams respectively, wherein the lasers are distributednon-uniformly along the vertical direction from a highest to a lowest ofthe lasers; an optical splitting apparatus configured to receive andsplit the laser beams into a plurality of split laser beams withdifferent propagation directions, wherein at least some of the splitlaser beams overlap; and a receiving apparatus configured to receiveecho beams to detect a target, wherein the echo beams are a portion ofthe split beams reflected by the target.
 17. The Lidar system accordingto claim 16, wherein: the Lidar system is mounted on a vehicleconfigured to move on a surface and is rotatable with respect to avertical axis relative to the surface; the emitted laser beams areparallel to each other and propagate in an emission direction; theemission direction is parallel to the surface; when the Lidar is notrotating with respect to the vertical axis, the split laser beamspropagate in a vertical plane and the Lidar system scans a distantvertical line of laser beam spots corresponding to the split laserbeams; a concentration of the laser beam spots first increases and thendecreases along the distant vertical line; and when the Lidar systemrotates with respect to the vertical axis, the Lidar system changes fromscanning the distant vertical line to scanning a distant verticalsurface.
 18. The Lidar system according to claim 16, wherein: theoptical splitting apparatus comprises at least one of: a one-dimensionalDammann grating, a two-dimensional Dammann grating, an optical fiberbeam splitter, a plane diffraction grating, or a blazed grating.
 19. TheLidar system of claim 16, wherein: the light emitters include a firstgroup of light emitters disposed along the vertical direction at equalintervals and a second group of light emitters disposed along thevertical direction at equal intervals; and the second group of lightemitters is disposed at positions corresponding to the intervals of thefirst group of light emitters.
 20. The Lidar system of claim 19, whereina number of the second group of light emitters is fewer than a number ofthe first group of light emitters.